It has been pretty much covered but...
Wordpy, for blogging on the go and upload to picasa/flickr
Transmission, the bittorrrent app
Mytube, to watch Youtube videos
Skype of course
Vgba, with Zelda and Advanced wars
Vagalume, for last.fm playback
Personal menu
Load applet
Other maemo weather

And I think these are just the very first if my favorites (excluding the ones already mentioned)