Damn, I thought I went overboard on apps.
Some of the ones I use often:
GoLauncher - UI replacement. Easy to theme.
GoSMS - find it better than the stock text messanging app
Widget Locker - Lockscreen customization
Plume - Twitter client, although the official Twitter client is pretty good
Friendcaster - for Facebook, the official Facebook app sucks on Android
Kik - Instant messaging. Doesn't use up text messages. Cross platform (Android & iPhone). Allows group chat, pictures, videos, etc.
Soundhound - will listen to any song and tell you the artist/song title/album/etc
Pandora
TuneIn Radio - listen to almost any radio station across the country
Executive Assistant
Tapatalk - makes it much easier to read forums on your phone, how I wish ASFN was compatible
Netflix
Break.com app
Dolphin HD - internet browser
Sudoku 10,000
Plants vs Zombies
ESPN Scorecenter
IMDB
aCar - keeps track of when your car needs maintenance (i.e. oil changes, tire rotations, etc.)
Gentle Alarm - This will change the way you wake up. It's designed to wake you up when your sleeping cycle is in a light phase. That way you aren't jolted awake. It explains it here -
https://market.android.com/details?id=com.mobitobi.android.gentlealarm&hl=en
Amazon Kindle
Get the Amazon Android Appstore as well (instructions on Amazon website). They have a "Free App of the Day". I've gotten many paid apps for free this way.
Root only apps (basically hacking your phone. I suggest researching it quite a bit before actually doing it, it does void your warranty)
ROM Manager
Titanium backup
EDIT: Oh yeah, keyboards: I'm using Swiftkey X. Thing is a freaking mind reader. It knows what I'm going to type before I do half the time. I really like Swype too (trace keyboard instead of tap).