Epocrates (the free one) is all I really use as far as stuff you d/l.
DopeWars is very good for passing time before rounds. You buy and sell cocaine and heroin and fight police.
My PDA came with a WordToGo program so alot of times I'll type up my own little guides to stuff, convert them, and upload. It's especially good when you are "reading around you pts" to outline that NEJM article and keep it on your PDA.
I bought a Palm Tungsten E2. It's cheap and basic, I think it is way to easy to spend $450 on something you don't use that much.