Claire Broadley, has a useful list of the top 50 Google penalization triggers which may cause a penalization for your web site.

These are the most common reasons for Google to penalize your site and while the definite reasons for a penalty may not be all clear, the factors listed in this article definitely contribute to put you in the high-risk group.

Useful. resourceful. 7/10

Full guide to Google most common penalty triggers: http://blog.kissmetrics.com/penalized-by-google/

Mozcast is a free data reporting service which allows you to see general trends and symptoms indicating whether Google is making significant changes to its search ranking algorithms.

MozCast has been designed to help you keep track of the day-to-day changes in the Google algorithm by tracking a hand-picked set of 1,000 keywords and by grabbing the top 10 Google organic results.

These are compared with the previous day's top 10 (for any given keyword), to produce something that looks like a temperature (in °F). An average day is about 70°F.

Free to consult.

Try it out now: http://mozcast.com/

Learn more about how it works: http://mozcast.com/about

(Thanks to Donnie Strompf for kindly suggesting it)

Easily find out if your web site or blog has been affected by one of Google algorithm updates such as Panda and Penguin. Next to the excellent Panguin Tool, now you have an additional tool to make sure you have not been hit.

From the official site: "AlgoSleuth harnesses the power of the Google Analytics API to provide a powerful analysis of your site’s organic traffic and highlights all major Google Algorithm updates that may have affected you over the past several years.

The tool includes all major Panda and Penguin updates from January 2011 to today.

The process for extracting your data takes, on average, just 2-3 minutes. After that, you can use AlgoSleuth to query results for one or any number of Google Analytics profiles."

Harsh Agrawal has also posted a useful intro tutorial to AlgoSleuth, which you can find here: http://www.shoutmeloud.com/algosleuth-find-which-google-panda-update-affected-your-website.html

He writes: "AlgoSleuth uses the Google analytics API to fetch traffic details from your account, and matches with known Panda & Penguin updates to verify whether you have been hit by a Google algo update."

(Source: Shoutmeloud)

Free to use: www.delegator.com/algosleuth

Good advice from Neil Patel on QuickSprouts on the risks involved in focusing excessively on low-quality guest posting and at the other pros and cons that such link building strategy brings.

Although Google Penguin 2.0 isn't here yet, it is quite likely that it will focus on some of the very issues outlined in this article.

Informative. Rightful. 7/10

Full article: http://www.quicksprout.com/2013/04/18/penguin-2-0-how-guest-blogging-will-be-affected/

(Image credit: www.empowernetwork.com)

Here's an excellent visual poster illustrating the key differences between the type of SEO activities that were effectve back in the days before Google Panda and Google Penguin made their first appearances, and the ones that are appropriate and effective today.

Things have changed a lot in these last two years, and this visual diagram does a great job of reviewing and synthesizing what has really changed.

Whether you are new to web publishing or have a long established web presence, I think you will find lots of valuable information in here as well as many confirmations of things you thought but weren't sure of when it comes to SEO.

Up-to-date. Factual. Informative. Must-read. 8/10

Full visual poster: http://www.zealousweb.net/blog/new-approach-to-seo/

(Thanks to Marty Smith for finding this gem)

Jeff Foster has a point and I do agree with him. His concern is indeed appropriate.

He writes: "Just as low-level article directories (ezinearticles, articlesbase, and others) got hurt by Google’s Panda Update in 2013, I predict that Google will hurt sites abusing guest blogging in 2013.

I don’t feel guest blogging is bad, nor that all bloggers who do it will be penalized by Google.

SEOMOZ.org allows guest blogging and their rankings increased during the Panda update.

But when SEO companies start to abuse any link building tactic, you need a preventative plan in place because an update from Google will be coming."

The article provides great advice on how to manage guest posts in ways that guarantee maximum safety for you and minimum risks of being penalized because of them.

Very useful. Informative. 8/10

Full article: http://www.problogger.net/archives/2013/02/15/why-blogs-that-allow-guest-posts-will-be-penalized-in-2013/

If you wonder whether your site has ever been penalized by the Google Panda or Penguin updates, you don't need to guess anymore. You can check and be sure of whether any of the Google updates has ever affected your web site by simply using this free tool.

Panguin, this is how it is called, is a web-based tool that allows you map the dates of each major Google algorithm update, including each Panda and Penguin update over your traffic graph inside Google Analytics.

To check it, it takes less than one minute.

Highly recommended. Great tool.

Free to use.

http://www.panguintool.com/

(Thanks to Ryuichi Sakuma of Metaline for suggesting it)

Google has announced this week that its web search engine is now being driven by a new algorithm, officially known as Hummingbird.

The transition to the new algo took place sometime during August, and it affects approximately 90 percent of worldwide searches.

The Hummingbird algorithm focuses on understanding the meaning of more complex inquiries, according to comments from Google's senior VP of search, Amit Singhal. 

Read more: http://www.reuters.com/article/2013/09/26/net-us-google-search-idUSBRE98P11O20130926 

FAQ on Google Hummingbird: http://searchengineland.com/google-hummingbird-172816 

Check whether your web site was positively or negatively affected with Fruition: http://fruition.net/google-penalty-checker-tool/ 

If you want to learn more about the risks that "unnatural" links can cause to your site, here's an good resource to check out: a curated selection of ten clips focusing only on this topic: links and Google penalties.

The collection includes:

7 selected videos from Google Matt Cutts

1 clip with Rand Fishkin - SEOMoz

1 clip with Shane Walker

1 additional video

Useful. Informative. 8/10

Full list: http://umain30.com/2013/08/14/10-top-videos-on-unnatural-links-and-penalty-warning/ 

Google has updated its algorithms again yesterday, and by looking at the amount of changes in the SERPs this does not look like something minor.

According to the research and analysis done by Dr Pete on the MOZ blog, the web sites that have been most affected are those that utilize in their domain name some of the keywords for which they are being searched for.

These are called PDM (partial domain matches) and data shows that these have all been strongly affected.

So, if you own a web site that utilizes some of your niche keywords in its name and have seen a sudden drop in traffic or earnings since yesterday, check out the thorough analysis that Dr. Pete has done and see for yourself what is really happening.

From the article intro: "If you follow our MozCast Google "weather" tracker, you may have noticed something unusual this morning – a record algorithm flux temperature of 113.3°F (the previous high was 102.2°, set on December 13, 2012). While the weather has been a bit stormy off and on since Penguin 2.0 and the announcement of 10-day rolling Panda updates, this one was still off the charts: "

Informative. Useful data. 8/10

Full article: http://moz.com/blog/early-look-at-googles-june-25-algo-update

To monitor Google algo changes and updates there is a new free tool which visualizes on a day-by-day basis the "turbulence" (quantity of movement) of thousands of keywords inside Google SERPs.

When the turbulence gets high you know that Google has made some changes.

Free to use: http://algoroo.com/

Similar tools: Panguin Tool - Algosleuth

Google is getting smarter every day, and it makes little to no sense at all to keep going after links like it was 2005.

In this very interesting article by James Finlayson on SEOMoz, you can get a good idea of how Google thinks and looks at your inbound linking profile when looking at your site.

Better understanding link quality, type, position and authorship can help you a great deal in saving yourself not only lots of time and money, but also the risk of having a site that is penalized.

The best strategy of all in my opinion is to build oustanding, uniquely useful content, ike no one else in your niche does.

Informative. Insightful. Very useful. 8/10

Full article: http://www.seomoz.org/blog/how-guest-bloggers-are-sleepwalking-their-way-into-penalties

If you have been hit by a Google penalty, whether "manual" or "algorithmic" here is some useful information for you.

Danny Sullivan reports on how the link disavow tool works and what you should expect from it, in terms of how much time it takes for the tool to process your submission as well as how much time you should wait to see some benefit to your site.

Useful info, clearly explained. Bravo Danny. 8/10

Full article: http://searchengineland.com/how-google-disavow-link-tool-remove-penalties-154928

Here is a detailed report by founder Lewis Sellers, of how his web agency in the UK, Pinpoint Designs, got hit by a Google penalty without having consciously done anything tricky, and how it gradually found a way to get this penalization revoked.

Key takeaways:

1. Start by building up a list of all the links pointing to your website - This is extremely easy. Login to Open Site Explorer, Google Webmaster Tools and use other websites such as Ahrefs or Majestic SEO. ...
   
   
2. Work to remove those links hard - Removing links isn't easy, there are numerous sites out there that will help remove links from you, but it's a fairly slow process. ...
   
   
3. If you can't remove links - If you can't remove links, use the Google Disavow tool. That being said, don't use it unless absolutely necessary. ...
   
   
4. Write good quality content - Show Google that you can write good content. Make sure that all the content on your website is unique, up to date and interesting...
   
   
5. Spend time on your reconsideration request - Google must receive hundreds, if not thousands, of reconsideration requests each and every week. Rather than sending in a paragraph, spend some time telling them what you've done wrong and most importantly, be honest. Tell them why you think you've been targeted, what you've done to rectify it and how it won't happen again.
   
   

But there is a lot more useful stuff in the article, including all the steps taken, tools used and what to do if Google says no to your Reconsideration Request.

Interesting. Useful. Informative. Resourceful. 8/10

Full article: http://www.seomoz.org/blog/lifting-a-manual-penalty-given-by-google-personal-experience

Two years ago today Google Panda hit thousands of web sites bringing them to near oblivion in a matter of hours. After two years most of the sites that were originally hit by this Google penalty are still suffering from it, and there are only a small number of cases where the site has been able to recover fully its pre-Panda traffic levels.

"Two years ago today, Google sent shockwaves through not only the SEO industry, but also through online publishing in general when it launched the Panda algorithm update.

It was originally called the “farmer” update because Google’s prime target was “content farms,” a name used to describe sites that created high-quantities of low-quality content that sometimes ranked highly in Google’s search results.

...

As you’ll see below, on a list of nearly two dozen of Panda’s original losers, only two websites have returned to the SEO visibility that they had about three weeks post-Panda. The others have all continued to lose search visibility.

Some other Panda-hit websites have recovered, though not all of those recoveries have been permanent. We’ll look at all that later in this article."

Informative. Good real-world cases. 7/10

Full article: http://searchengineland.com/google-panda-two-years-later-losers-still-losing-one-real-recovery-149491

If you have been hit by a Google penalty, this may have been triggered by the number and type of links that are pointing to your site. Given the new quality standards Google is after, it may be a good idea to clean up any inbound link that is at risk of compromising our site trust.

From the original article by Jesse Woodhouse: "If your website has been impacted by “garbage” links, you may need to take a street sweeper to your backlink portfolio.

Seeing a drop in traffic or rankings can be concerning, especially when it happens suddenly.

If you have noticed this, chances are your were affected by a Google algorithm update or penalty.

If so, then you may need to consider pruning your backlinks by finding low quality or harmful links pointing to your website and then remove them. Doing so can help you put your website back on a road to recovery."

Useful. Excellent, illustrated advice for who is new to this. 7/10

Full article: http://www.seo.com/blog/how-to-take-a-street-sweeper-to-your-backlink-portfolio-2/