1.
Launcher Pro Plus - Greatest alternate launcher out there. Brilliant work by the dev, absolutely worth the price for the pro version, even though I don't use the pro features.

2.
Dolphin Browser HD - Just a great, clean, professional browser.
3.
Widget Locker - SenseUI lockscreen on my Droid? Yes please!
4.
Wireless Tether for Root - 'Nuff said. I don't tether on a regular basis, but it has come in handy on more than one occasion.
5.
Google Talk - I convinced a friend of mine all the way across the United States to get an Incredible. Now we just use Google Talk way to much. What have I done?!
6.
Shazam - Amazing. It's ability to identify music even with voices and background noise over the recording is absolutely incredible.
7.
Sensorly Map Viewer - Maps real signal strength using the GPS, then uploads to a central server and color codes maps to display true signal strength across the country. AMAZING app, it's a true shame that more people don't use it.
8.
AIM - Funny thing is, I use the official AIM app for Facebook chat only, and I use Hi AIM for AIM when I need it. Haha!
9.
Pandora - Music. Yay!
10.
Gameboid - Come on, who
hasn't completely drained their Droid's battery life playing Pokemon?