Tear plus Advoid is terrific for browsing the web.
Kchmviewer is awesome, awesome, awesome since I'm no longer lugging around books like I used to.
Garnet VM I use almost daily with the huge database of apps I have for it.
Xkbd finally works with no repeating keys like it used to. This opens up so many more opportunities of being able to use programs that weren't possible before.
Xbindkeys is easy enough to map new functions for the few hardware keys on the tablet including launching apps with a single press of a button or enabling a right mouse click.
Watching videos does somewhat blow. The best results I've found are watching cartoons like the Simpsons.
Many choices for playing audio files. I don't have all that much music but I've got a huge folder of Kaplan lectures I listen to.
Pidgin rocks especially with qwerty's LED notification.
Dial Central probably saves me around $300 yearly for making phone calls and sending and receiving SMS messages.
For stress relief, I usually enjoy Dosbox (currently playing Castle of Dr. Brain on expert level) and I still enjoy old school Telnet games with ADOM being my favorite.
Of course there's always SCUMM as well.
Shin Megami Tensei 1 and 2, Wonder Project J, Front Mission and Wizardry Trilogy works really great on the little handheld. Kirby's Dream Course works okay.
SCID lets me watch international matches live between two Grandmasters with an analysis engine running in real time which is quite entertaining for me.

I feel like I'm still leaving out about a couple of dozen more things that I haven't mentioned.