I got a cheap Bluetooth dongle from Hong Kong yesterday, and it seemed to work fine on my xp laptop, though I had to use the setup program that came with it to get it recognized. Then on my Ubuntu (mint) desktop computer it just worked with not much setup at all.

But now that I have it, what can I do with it? I pushed a pretty big book and an mp3 file onto my N800, but haven't so far been able to browse any files on the desktop computer from the N800.

Unless I buy some hardware, what else cool can I do with bluetooth other than get and put files? I can do that with my wireless already.

bluetooth keyboard, bluetooth cell phone modem (EV-DO).
you can also install x11vnc server and use vnc to access your N800.
you can also install xterminal and ssh--using ssh to access any other device running sshd