http://club.live.com/home.aspx Basically, you play microsoft's shitty flash puzzles, that have a search engine attached to the bottom to earn "tickets". These tickets can be used to win free stuff, such as music, a 360 controller, T-shirts, a Zune, a 360 with free x-box live and games. For a full list of prizes (updated sometimes) go to https://club.live.com/get_prizes.aspx. The puzzles are sometimes hard as shit, and at the moment me and my friends are trying to snag some 360 controllers for Cortex Command and PC games.
There are automated marcos for some, and cheats for all of them, so just ask.
Here are the ticket tallies for the games currently available:
Lexicon 25 tickets
Chicktionary 20 tickets
Crosswire 20 tickets
Clink 10 tickets
Dingbats 3 tickets