Here is a sample of what I have, there are some more but these are the ones I use the most:
Shazam, Pandora, Facebook, Coin toss,
Windowcast - Set a few basic parameters (ideal temp, cloud coverage, humidity) and the app basically gives you a thumbs up or down if today will be what you like.
The Weather Channel - for when you need to know the details of the forecast.
Tweetdeck - Used to update Twitter accounts. You can have multiple accounts and control them all from one app.
Linked in - Keep up on your linked in accounts
Evernote - note taking software. Voice notes, Picture notes, text notes, back-up to your computer and you can share.
Cardsnap (lite) - Create contacts by simply snapping a picture of their business card. 3Gs works great with the camera, 3g needs to have the
Griffin Clarify case. I have it on my 3g and it works awesome!
OpenTable - make reservations at local restaurants and earn points redeemable for dining deals.
ESPN score center - Get up to date scores across many sports. You can add your favorite teams so they always appear at the top of the list.
iFitness - track your workouts such as reps, weight, exercises done that day. Also has built in routines and graphing. easy to back up. I LOVE this app.
Fandango - Find movies, watch trailers, order tickets.
Urbanspoon - find random places to eat in your area.
FML - easy to access to everyone's favorite "feel better about myself" site.
Yahoo fantasy football '09 - track your team with live scoring and make changes to your roster. supports multiple teams.
MLB at bat 2009 - listen to live games and watch highlights shortly after they happen.
Nervsounds - Toolbox of annoying sounds such as fingernails on a blackboard, mosquito, fork on a plate and more. Drives people nuts!
Bump - transfer contact information with a simple fist-pound.
Lightsaber - the name says it all. motion based sounds and everything!
Drinks free - 5000+ drink recipes
Guitar chords - cheat sheet will finger layouts and tabs for all major guitar chords
My Delicious - Keep track of you bookmarks for surfing the web. This way you will have them at any computer you are at.
Snatch - virtual mouse for your Mac. includes a track pad with both right and left mouse clicks, keyboard and completely customizable control layouts
Dog Whistle - just as it is labeled. really mess with your friends or neighbor's pain in the a$$ dog!
Picturesafe - keep those personal pictures lock up and out of your camera roll so prying eyes do not see them. Password protected.