Google Penalty World

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/