I have been quite addicted to Pocket Legends lately. It is a really fun MMO game on the iPad. You can download and play the first area for free, then after that you need to buy dungeons or packs of dungeon. I bought a Ten Dollar (75 Tokens) in game money pack to buy dungeons. Now they have a bundle of the first four dungeons for 18Tok, Ancient Swamp(currently the highest level) is 10Tok, and they just released two PVP arenas for 10Tok each. There is no monthly fee and it is a ton of fun.
As for Angry Birds (HD), this is not the place, but just wanted to mention I love that game and it is one few applications that I have seen scale perfectly using the J/B hack.