Did you look at Songbird [1]? Made by Mozilla, the same people who bring us the firefox browser.
I tried this over a year back to simply play music off network devices on a Linux lap top, and for that it worked really well. I didn't get around to using this to sync up the ipod though. Their website claims that they can sync to many music devices not just the iPods.
My issue with iTunes was it was not able to watch the music directory for new mp3's being added, so if someone else added a new album in there iTunes didn't pick it up unless I told it to rescan the directory. Songbird had this feature which I liked.
Cheers
[1]
http://getsongbird.com/