Snopes.com

One of the best Urban Legend sites is Snopes.com. The site covers a wide variety of Urban Legends from the War on Terror, animals, science, the business world and even Disney:

Light a candle tonight for a memorial satellite photo (false)
Someone is mailing out sponges soaked with a deadly virus (false)
The tip of Disneyland's Matterhorn houses a basketball court (true)

We recommend taking a look at the following categories on Snopes (with examples):

Rumors of War (6,000 travelers get stranded in small Canadian town - TRUE)
Animal Stories (rice thrown at wedding is dangerous to birds - FALSE)
Marketing 101 (M&M's could have been the candy in "ET" - TRUE)
Pregnancy (men can get pregnant too - FALSE)
Disney (a hidden private club exists inside Disneyland - TRUE)
Television (Life cereal's young Mikey died of pop rocks & soda - FALSE)