A little more general than the Urban Legends Reference, purportal.com is a great place to stop by before you forward your next email.
Their main page contains handy search boxes to search the above-mentioned Urban Legends Reference Pages, the Symantec Virus Encyclopedia and a couple of others. They also provide a handy list of links to reference sites—long enough to be complete, short enough to avoid being overwhelming. It definitely looks like a great starting-point for figuring out if information is good or bad.