A while back, Microsoft introduced a nice system to purchase and queue up game downloads for your Xbox off of Xbox.com.
A particularly fantastic game launched yesterday, but slipped past my radar. So today, I decided to buy it on my lunch break. That way when I turned on my Xbox when I got home, it would automatically download and I could start playing quicker.
The Xbox Live Arcade operates on a points system. Basically you purchase credits with real world money. The problem is, that you often end up with left over credits that don't really amount to anything. You might have 450 credits and the game you want it 1200. Invariably you end up having to purchase extra credits to be able to afford that next great new game.
What I like about purchasing online is that there is a contextually relevant alert at the top of the purchase pop-up. It tells you exactly how many more Microsoft Points you need to make your purchase. Since points can only be purchased in bundles, this is useful to know which one to pick without having to do the math in your head.
Although I still prefer the Playstation Network's cash and carry method, this lessens the pain of using a credit system a little bit.