I've always done very little backlinking. Some social bookmarking, plus my own blogger site that I created to point back to the money site, plus some hubpages that serve the same purpose. And Ezine Articles. Just a little BMR links, and that was at least a few months before they closed.
I don't have Google Analytics or Webmaster tools, so don't know if I was actually hit by a penalty, but something unpleasant has definitely happened.
Should I go to my blogger site and remove links, plus remove the links on hubpages? And delete bookmarks?
And what about our signatures on this forum?