I have all my music files on an external hard drive. The hard drive is fed/accessed both through an old ibook and an imac - both have selected the external hard drive as the itunes folder. New songs uploaded to the external hard drive using the ibook don't automatically appear in the itunes library in the imac, and vice versa. So need to access the external folder and click the music file at issue for it to appear in the itunes library of the machine that wasn't used to upload it. Cumbersome. Any idea how to keep the respective itunes libraries in sync with the external hard drive?
The new version of iTunes has a "Automatically Add to iTunes" folder under your iTunes Music folder-- if files are placed in there, they automatically get added to iTunes if it's running or starting up. Not a perfect solution (I'd much rather iTunes work like Zune's software, where you can define folders of each type (music/video/podcasts) to monitor) but it might work for you. Otherwise you'll have to find a third-party solution.
I don't have this problem, but I remember reading on lifehacker that there's a tool you can download for this. Try searching on "iTunes Library Updater."