In a lot of ways, the Nigerian scam resembles the Pigeon Drop.

It's always been one of my favorites - the thing about a good PD is that it doesn't take much sophistication to run, and can be done with just about any level of mark.

There was a good variant on this one in a Western Union office in the classic Mamet movie "House of Games".  Not exactly the Pigeon Drop, but many of the same elements (except focusing on reciprocity as the exclusive impetus, rather than the third party element).