RottenNeighbor.com allows the general public to write reviews about their neighbors. These can be positive (green) or negative (red) - but the site's name should be a tip-off on which approach is the more popular.There is also a nice rundown on where the sex offenders are, as well as an attempt to list foreclosures (yellow).
Of course, all this is ripe for abuse and slander. Expect an inevitable flurry of lawsuits.
