Microsoft has introduced a rewards program for US and UK Xbox LIVE members. And, for once, you can be a Silver (free) member and still get in on the action. What it boils down to is this: spend money on various XBL-related services and goods, and get a fraction of that money back in the form of Microsoft Points.
There's an overview of what the program entails right here. Those point totals might not seem like a lot, but if you sign up for this and sort of just go about your daily routine, I could see the program paying for the odd Rock Band song here or there. Why the heck not?
Introducing the Xbox LIVE Rewards program [Major Nelson]