At last, the chains that bind an auto-synced iPod have been broken; or at least, this is the first time I've heard of such a simple hint for adding music (and possibly photos and video) to an iPod already bound to another computer's library. Mac OS X Hints has a surprisingly simple tip
for accomplishing this: all you need to do is select and expand the iPod icon in the left Sources menu, then simply drag from the Finder whatever new music you want to add onto the main list of music, *not* the iPod in the list. This can be useful especially for those who have separate libraries on two machines (example: one for work and another for home), since the only other simple alternative is to set the iPod for manually managing your music, which then doesn't allow you to sync some metadata like ratings and comments or tags. Oh what a twisted music management web Apple weaves.
A commenter at Mac OS X Hints says
they can add photos and videos using this method as well, but I unfortunately don't have a second machine to try this out on right now. Anyone in the audience care to give it a go?