You receive an e-mail and want to know if it is accurate before, possibly, sending it on to a friend. Check out either of these two site:
Truth or Fiction or
Each of these sites allow you to enter information from the e-mail, such as the subject line or a brief description of what the e-mail says. You can, then, "search" and it will give you an explanation of the validity of the claim.
Snopes, also, has a "Top Scams" section, which highlights current scams of all kinds, not just e-mail scams.