Don't download keygens.

"Key generator"--supposedly, it generates keycodes that are used to unlock full-featured versions of purchased software. However, some keygens actually just spit out a random selection from a list of pre-generated keys. This is especially a problem on Steam since such keys correspond to actual Steam activations of copies of a game, so this ends up denying someone else use of the key.

With the amount of fake YouTube vids and such, I'd say so.