it really all comes down to how you use it. I think the Google Mobile App is pretty much a must have for me, no question (everything from maps, to Gmail). A lot of people like Viigo, as an all around good tool, though i just find it excessive. If you like having a second browser (say.. reading an article, and wanna look something else up w/o losing your spot) Opera Mini is fantastic, though some people like Bolt browser, as another alternative. I also have the BB version of GoogleTalk, from BB’s own website, just because i need to be connected, and it works almost as smoothly as BB Messenger. Also, from the App Store, you can get a free app called QuickPull, which simulated a battery pull.. i.e. a real restart, not a fake-o blackberry restart. Definitely a useful program. Game-wise, I’m a tetris-o-holic.. but i didn’t wanna front the cash for actual tetris.. but if you Google search Jetris, it’s a super good tetris clone. (SUPER good, for being free and all).
That’s about it, for me.. used to have a bunch more, but i run pretty light now, as a lot of the stuff just ended up being clutter.