Building a generator can be a fun and fairly simple project. Getting a large DC motor however can sometimes be difficult. Here is a writeup on how to make a generator from an old washing machine drive. It looks like you might need to find a specific machine called the “Smart Drive” to follow their directions exactly though. If you happen to find one, or know of a unit with a similar motor, you can follow these directions to end up with a fairly decent wind powered generator.

[thanks TripleB]