Just to help you get some started, some stuff you should look into getting:
Amazon App Store (especially for the free daily app)
Dolphin Browser HD (some argue a better browser than stock)
ES File Explorer (especially good if you want to access files on your network)
Folder Organizer (let's you customize icons and create folders)
FriendCaster Tab(Facebook app optimized for Honeycomb)
JustReader (pretty good RSS Google reader)
Pulse (a very flashy RSS reader, nice to show off)
Komik (great comic book reader for cbr and cbz files)
News360 (grabs news from a bunch of sources, optimized for Honeycomb)
Some sort of dual battery widget so you can see the power level of the dock too
Wizz (a bunch of widgets for Calendar, agenda, mail, Facebook, Twitter, etc)