Yet another iTunes Remote, but this one really rocks: Ovolab RemoteTunes.
A cocoa application that will let you play, pause, skip, create playlists, edit tags, as if you were in front of iTunes. What more, you can also activate iTunes visual effects, create or change playlists, change the equalisation settings or rate your songs!
Ovolab RemoteTunes can access the remote iTunes Library directly to speed up performances (via filesharing), or loads the playlists and tracks info during connect. Unfortunately, I didn't manage to make the former option work, and the latter can take a while depending on the size of your library (it took 3 minutes for RemoteTunes to import the info from my Cube/400 in the background - I have over 5'500 songs).
The remote Mac needs to have Remote Apple Events turned on (Sharing System Preferences).