There are several app specific sections of the forum starting with (apps) where people have discussed at length what they like and don't like. You may want to start there.
Apps I can't live without:
Google Docs
GMail
Evernote (on-the-fly note taking)
Kindle
Any.Do (Task management)
KeePassDroid (password management)
Google Goggles (closest thing you will find to a QR code reader)
Google Sky Map
Wi-Fi Analytics
Netflix
AngryBirds of course
Wind up knight is a fun platform type game
I was able to get flipbook to work but they were still tweaking it for tablets.