get ready because here is my list that i have and highly recommend:
Google Voice (if you have an account) -- this is service provided by google so you can research it online
Twidget Lite (widget) -- twitter client that runs as a live widget on your phone's homescreen
Dolphin Web Browser (quite possibly the best mobile browser i've ever used on any phone)
Advanced Task Killer -- app that allows you to end programs that are running which you may not be using. i use it to free up memory
Astro file browser -- lets me explore files on my phone
B&B Quick Uninstaller -- the best program to use to uninstall apps from your phone
CNET scan and shop -- you can take a pic of a barcode on a product and it will search CNET.com for the best prices and reviews on the product
Documents To Go -- allows you to view MS office documents
Fandango -- you can look up movie times at any theater and buy tix as well
Google Goggles -- search google using an image
Listen -- lets you download/stream podcasts and other audible media (another google product)
Live Scores -- check scores of any sport with live real-time updates
Open Table -- lets you make reservations at restaurants online without having to call
Pandora -- free online radio, but i still prefer grooveshark
RSS Widgetboard (my news widget) -- lets you have your fav news sources on your homescreen with auto live updates
Shazaam -- if you hear a song that you don't know you can hold the phone up to the speaker and it will find out the artist and name of the song
SMS Popup -- best app i have --
Tipper -- calculates tip amount
Ustream broadcast -- lets you watch Ustream streams on your phone. but you need a 3G or WIFI connection to watch. i'm hoping to try this out for the next juve match
Weatherbug (widget) -- weather on my homescreen
Yelp -- restaurant/bar reviews by other people. it comes in handy when trying out a new place
Where's my droid -- helps you find your phone if you lost it and if its on silent