Why can't they be combined? It's not like iPods are short on space or anything,so that's a little like sharing a bedroom and stereo but not insisting on keeping your CDs in completely seperate places.
2 Computers? In that case you'd have to manage the iPod manually, as most to every utility that will sych for you will delete files that it isn't assigned to. You can each use iTunes on a seperate computer, but you each have to drag files on and off manually.
Make plenty of playlists if finding what you want to hear becomes a problem, and it wouldn't be a bad idea to make a playlist out of each library if you're the type to listen to library wide shiffles.
