Google just released ( 16 October 2012 ) a great tool in Google Webmaster Tools: Disavow Links
How to use Google Disavow Links
If you have done black/grey hat link building in the past and you got links from low quality websites and you got penalized, you might have struggled to remove those bad links but you couln’t because webmaster’s didn’t reply or other reasons.
Now it is really easy to tell Google to ignore those links from GWT Pannel and Access Disavow Links
You can upload a file with the links that you want to ignore. Upload each link on a single line.
What do you think about this tool? Is it useful for you?