Wikiamo, Stanza and Ereader, the iPhone is brilliant for ebooks, and there’s loads of free classic stuff around as well as paid for stuff, WeatherPro, Tube Deluxe, Genius, which is a better camera app than the standard one, Camerabag, Wordbook, WunderRadio, Tioti TV+, Flixter, FreeMemory, iPhone the Missing Manual, London Mini AtoZ, Clinometer…
There’s plenty more but those are ones I’ve found useful. The camera is better than it appears, and apps like Camerabag and Photogene, Photolab and SPPhotofix let you sharpen, alter colour and contrast and crop in the phone, then you can upload directly to Facebook, (another free app), and Flikr, via Mobile Fotos. There’s loads on there, plus you can set shortcuts to your homepage from webpages; I’ve got several including STW, Megatokyo and Metcheck. Brilliant device, and I’d recommend a pair of Ultimate Ears SuperFi 4Vi phones as well. They’ve got a mic on, plus pause and answer button, along with the best sound I’ve ever heard from in-ear phones. I got mine from earphonesolutions.com. They’re $124 but worth every last cent!