Things I use most, so top of my list would be:

Katana (or a Bible reader)
Maecount (I've already spoken to the dev!)
Stoppish (or a timer of some sort)
Xournal
A handful of simple games (I use colorflood, Qthello, blocks)
Some sort of document reader that could handle standard .doc formats would be good.
MyPaint is awesome - though I'm not artist enough to make the most of it.
Anyone for MeeSheep?

Those would be my top pics. I'm sure people will think up other things. There's a project already looking at clever things with NFC and settings (I'd find the link but I'm already late for work!)