lexipixel - 6:15 pm on Oct 14, 2009 (gmt 0)

Craigslist puts up a "Please Flag with Care" box on all posts which includes links for flagging a post as: "miscategorized", "prohibited" and "spam/overpost".

I'm sure with very simple algorithms to count how many times a post gets flagged and by who (based on what IP is flagging the post), and the OP's email address & IP it has greatly increased the signal to noise ratio in their free posting areas and greatly reduced the amount of human editor resources needed to keep the boards clean.