Literally, best possible post on this topic. All the others (including mine) should be deleted and these recommendations should be stickied and we should just have CarlJ update
Let me just emphasize the need for "AppShopper." It's how I get most of my games free or $0.99 instead of $3, $5, even $12. Once you figure out how to use it and track the apps that interest you, you will save a LOT of money (that's IF you are into buying quality apps. doesn't make a difference if you are a cheapskate and only buy free apps)
+1 for AppShopper!