Also, any general apps at all that come under the category of "Every smartphone owner needs this"?
Yelp (for business reviews; Monocole feature lets you scan places nearby)
Maps/Navigator (Should be built in)
Call History (Lets you check your call history while on the phone, normally something you can't do on an Android)
Alarm Clock Xtreme (Makes you do math to turn it off. Works wonders if you're as lazy as me)
ASTRO (Lets you navigate your device in a folder format. Must-have, IMO)
ColorNote (Great for shopping lists)
Music Players I like: GoneMAD (has random album feature), PlayerPro (nice otherwise). Both of those cost money but have free trials. Cubed/3 is a good free one.
Kindle (should be built in?)
Reader (for Google Reader if you use it)
Skype
Swype if you find typing individual letters cumbersome like I do.
As a general rule: Not sure if you've used a smartphone before, but there's definitely a learning curve involved if you haven't. Some apps might seem crappy at first but will make sense as you adjust to the device.