Anatomy of a 419 scam
Courtesy of The Register, a detailed account of how one greedy fool fell victim to a 419 operation. One thing that comes across from this story is that some of these scammers have stepped up the sophistication of their operations considerably - no longer are they relying on letters in broken English from "Mrs. Mariam Sese-Seko" to reel in the gullible. Instead they set up fake online banks and go out of their way to make the whole setup look and feel like a genuine enterprise.
Of course, the blatantly criminal nature of the proposal being made remains essential to the scam, so it stays in - it's hard to go to the police to report those who defrauded you when you yourself were hoping to engage in an act of fraud.