Microsoft Space Bucks. It's like money, except they come in the form of bucks. Microsoft Space Bucks. You use them to buy games. If someone came up to you on the street and said, 'Hey guy, give me 12 dollars and I'll give you 15'. You'd do it right? I know I would. Well, EB is doing a deal taking 20% off 1500 Microsoft point cards, and with Fez and Trials Evolution out now, I'd say that's a pretty good deal.
The little disclaimer says that it's 'while stocks last' and for a 'limited time only, but it's a good deal if you're thinking about splashing on XBLA.