Snopes
The internet has spawned many things, among them is spam and porn and advertising beyond what other media outlets have accomplished or could accomplish. Okay, so spawned may be the wrong word...more at exacerbated. However, another thing that the internet has exacerbated is the urban legend, a story which, on the outset, looks plausible, it even sounds real, but its nothing but a fabrication. Well, there is a site out there which hopes to debunk such myths.
And, while your at it, watch Mythbusters on The Discovery Channel