http://www.gamrs.net is hosting a 4v4 and 2v2 Call of Duty Modern Warfare 3 tournament, both tournaments are free to enter, and here are the prizes for the winners:
1st place team: Each member will receive 1600 Microsoft Points (Code will be sent)
2nd place team: Each member will receive 3 Month Xbox Live Code(Code will be sent)
3rd place team: Each member will receive $5 Gamrs Credits for any future tournaments

The rules for the tournaments are located on the tournaments bracket page, when registering for this tournament make sure your team and one alternate is registered on the site and is on your roster, members who are not on the team roster will not be able to participate.
(alternates are not required, but last minute alternates during the tournament is not allowed.)
Also add your Xbox Live Gamertag to your profile on Gamrs.