GameStop Call of Duty: MW3 Pick Your Perks Sweepstakes
You can enter twice a day for every email you have. Make 30 emails for 60 entries a day, probably win about 2-3 times a day of either 160 MSP, $5 gamestop GC, or 1 month XBL.
I'll show an example picture:
See where it says "4110101000000000"? You HAVE to use that specific code.
Other than that, just put whatever.
Most of the time you'll just win a wallpaper (shitty one, at that), but you do have a chance of winning something.