My favorite app is Pandora hands down. 9/10
AOL Radio is great but I look forward to buying Tuner because it looks like more stream options are available.
Super Monkey Ball is fun...but can be hard to control.
Crash Bandicoot and MotoRacer unfortunately suffer the same fate only their control issues actually make it difficult to have a good time and it's very easy to lose control in both games.
Scrabble is AWESOME, but I'm a word freak. Cube Runner is extremely addictive like someone mentioned above. Great App.
MLB At Bat is my second favorite application because I am a baseball nut who needs updates on games on the go. I don't even like the other sports apps because this one is so far and away superior. I'm anticipating ESPN going on board with this soon so they might end up stealing the crown.
Band is disappointing. It's fun, but I'm not really persuaded to record anything I do.
AIM is AIM. Nothing more, nothing less.
Tomatoes, YP Mobile, Evernote, Facebook, Yelp, Eventful, NY Times, Google, Urbanspoon, Box Office, Dial Zero, midomi, reQall, Spanish, iPint, eBay and Check Please are all good essential apps. Great start to the App store.