More apps I have found...
Free (another post to follow with paid apps):
Dex Knows. Pretty self-explanatory. The phone book app optimized for mobile. Save numbers as favorites, find types of restaurants in the area where you are located using the "feelin' like" feature.
Bump. I found out about this from a colleague and I don't know how they do it.

If two parties both have the program, just hold your ipods in your hand and touch your hands together at the knuckles and voila! you've exchanged contact information!
FlightAware: flight tracking service. Requires registration but otherwise free. See radar images in real time of flights.
On my means: a budget tracking app. Recently used it to track my expenses at a conference I attended and it works great if you are just looking for a simple app.
U-Verse TV: If you are an At&t u-verse subscriber, you can use this app like the desktop version to set your TV recordings.
Games: I'm a big solitaire, mahjong and sudoku fan, so these may not mean much to others, but I have Free Solitaire 3D, Mahjong Solitaire by Sunsoft (free version only so far), and Sudoku by Mighty Mighty Good Games.
Tweetdeck: Just recently became a twitterer, and I find this app to be a good multipurpose app for viewing tweets, managing your twitter account and search for people you wish to follow.