I know that you can use it as a remote. At least if you are using Linux (or any *nix) on your computer.
ReMoot let you control Xmms, Amarok, Kaffeine, Banshee, Quodlibet, Totem, Xine, Juk, Rhythmbox, Noatun and Kmplayer from your N800 or any other web enabled gadget. ReMoot can also be used with your multimedia keybord keys.

It works pretty well! :-)