Nosy neighbors were thrilled last February when Zillow.com launched. Founded by Rich Barton and Lloyd Frink, the duo that created Expedia.com, Zillow.com uses square footage and recent comparable sales prices to provide free home-value estimates.
Zillow's success has led to copycat ventures, all of which have enormous voyeuristic appeal. Whereas real estate used to be a private matter, it's now possible to anonymously peak at the house values of neighbors, bosses, relatives, friends, and ex-boyfriends (not that I would EVER do such a thing).
Here's a round-up of some good sites for real-estate snooping: