Thought I would start a thread to expose any SE filters you've run into
Me:
2002 launched site, loved by Google tons of pages indexed and traffic, lots of links blah blah
1st filter - tried to get targeted anchor text to an internal category index page using blog comment anchor text like top ranking competitors were using - result was page knocked out of the top 200 for a time for that anchor/keyword and came back to its 70 ish position after a few months
2nd filter - recently bought site wide same targeted anchor text on a blog, looks like it tripped a -30 penalty on that anchor text
If it is that easy to trip filters on yourself, imagine what you could do to competitors (if you were that type of person). I am surprised G is being this aggressive.