Nigerian scam
I've been getting an awful lot of Nigerian scam spam email lately, with a surprising number of variants, but most of the general form "I have access to a lot of money, and if you help me get that money out of Nigeria, you can have some of it." I've known this was a scam for years, ever since the first time I got a handwritten letter via international postal mail from Nigeria, but I always figured it was like Make Money Fast, the sort of thing that an individual scam artist learns about and decides to try for themselves. Turns out that no, it's a major industy (some unconfirmed online sources say it's anywhere from the fifth- to the third-largest industry in Nigeria), and there are dozens of variations. The U.S. State Dept. provides a bunch of info about Nigerian scams, and there are some entertaining sites where people are posting their email correspondence with the scammers.