Some of mine:
* Audiobooks (Free) by Traveling Classics — uses free Librivox recordings of classic books (where the copyright is expired), read by volunteers
* Evernote (which someone else mentioned)
* Photoshop.com Mobile — fun for airbrushing your photographic memories
* Kaleidoscope — fun for turning your photos into something beautiful but unrecognizable
* iReadMusic — teaches music reading skills, and helps you translate them to the instrument of your choice
* Camera Zoom
* Shopper — for shopping lists by store, aisle, location
* Nozbe — best to-do app I have found for GTD on the iPhone, but if you sign up for the online version, it gets pricey. I’m still debating that portion.