Echofon - Twitter client that also posts to Facebook and Myspace
Darkroom - Waits for the camera to be steady before taking a picture
Facebook- No explanation needed
Urbanspoon - What do you want to do for lunch?
IM+ Lite - IM client
Flickr - Yay...mobile uploading of pics taken using my phone
ComicZeal - Best comic reader for the iPhone, without a doubt
Pandora - Is it me, or has the audio quality improved drastically since it was first released?
FML - A decent timekiller when in the john or when you don't feel like being productive at your desk
Word Ace - Scrabble + Texas Hold 'Em = Awesome
Tap Tap Revenge 3 - Better interface than TTR2, but the free song selection isn't as good.
Tap Tap Revenge 2 - There are some songs on here that I still enjoy playing.
Super Search - Lets you search a multitude of different engines and websites (Google, Yahoo, Wikipedia, IMDB, etc.)
Google Earth - Hey, I can see my house from here!
The Weather Channel - The default Weather app is too stripped down for my tastes
AT&T myWireless - On the off-chance that I need to make a sudden payment or need to look at my account
Sleepmaker Waves Free - Noise machine that the wife and I use when we stay at a hotel or someone else's house
iheartradio - App that lets you tune into Clear Channel radio stations across the country. I use this so I canlisten to the Bob & Tom while at work.
Craigsphone - Craigslist app
Words with Friends - Scrabble app that my wife loves
Low Grav Racer 2 - Very much a
Wipeout clone, but it's very well done. It's currently free on the app store, so grab it while you can
Heavy is good, heavy is reliable. If it doesn't work, you can always hit them with it.