Not sure if this is touching on the obvious or not, but if you want to sync specific users, just make one group called IPOD and drag all the people into that group, (it does not move, it bookmarks) and then tell the ipod to just sync that group. and then ignore the group on the ipod and just look up the users alphabetically which I think is what you're trying to do?
There has never been an option to specify specific photos or contacts. You CAN select specific movies however. Maybe you were thinking of that?
