Dolphin is definitely a must have, though the stock browser is pretty good as well.
Pulse is must for me, since there are several blogs I like to keep tabbs on.
Evernote works brilliantly on honeycomb, and easily syncs between my phone and home computer as well.
Documents To Go is my office app of choice, though Polaris is a great, built in option. I like DTG for it's ability to sync back and forth with Google Docs.
I use FBReader for eBooks on my DINC and have had no problems with it on the Transformer either.
If you want a great bible app, I really like Bible by LifeChurch.
That about covers it, as far as apps other than what comes on the device. These are my must haves, based on what I need my tablet for.
