New Ubuntu Desktop--what would you install?
nx: Htop for monitoring system resources in real time, VirtualBox for running different OSes, Wine for some Windows games and apps, Deluge as a BitTorrent client. Conky is a great productivity booster and nice on the eyes too.
Then get the packages needed for playing all media files, and I think that's about it.
Oh, I forgot, Pidgin rlz.