The Xbox live rewards program is great! I have collected 1260 (+20 pending) points from them so far. You have to get paid out at 100 points, but it doesn't take too long. You can do a 20+ ms point survey a month, and get rewards for doing things that you do on your Xbox already! If you have a number of achievements, you can get a discount on marketplace purchases, and a birthday gift!
I don't know about you, but I have 20 minutes a month for free MS points!