We all know the power of the Internet to virally spread untruths as well as truths... So if you need some Pulitzer-prize winning fact-finders to counter some of the lethal fictions circulating out there, check out www.PolitiFact.com. 

For particulars on health, check under the "chain email file"  , the promises about health on the Obameter, the Pants on Fire feature and a good overview of the viral chatter...

And if you want a lighter (but powerful) look at that viral chatter, read this great column by Ellen Goodman "In a wing-nut world, Granny's toast."