I love, love, LOVE my Droid!!! Here are some apps I like:
Advanced Task Killer -- kills the apps that are left running in the background, it's a MUST have.
Pandora -- acts like like the website, but hogs up the battery
Movies -- has NetFlix queue, local showtimes, upcoming movies, etc...
Ringdroid -- you can create ringtones from mp3s and other sounds you have on your phone
Uninstaller -- super easy to remove all those unwanted apps
WDW Lines -- you need to have a paid subscription, but it's WELL worth the $7.95 (and way better than Ride Hopper imo)
WeatherBug -- very detailed weather information
BatteryTime Lite -- tells you exactly how much battery power you have left
Jewels -- color matching game (great time killer)
Air Control -- direct planes onto runways (another great time killer)
DirecTV -- allows DirecTV customers to set their DVR at home from anywhere
Garage Sale Rover Free -- great, if you're into yard saling (shows you where nearby garage sales are based on your location)
Calorie Counter -- great if you're counting calories, lists calories for major restaurants and other food items