SuperSync is the best way to visually Compare and Merge multiple iTunes libraries.
All your music, movies, and playlists can be moved to all the computers you keep music on.
Features:
Optimized for iTunes and iPod users for Mac and PC
You choose which tracks and playlists you want to copy
Duplicate files are not copied twice
Unique color-coded Viewer lets you see local, remote, and synchronized tracks by color (gray, blue & green)
Works with hard drive libraries--import and/or export to an external drive, NAS, or DVD
Works over most TCP networks, including your local area network and the whole Internet
Customized for iTunes, but can work with most other media players and music servers
Library rescan feature finds broken links in your iTunes library and adds tracks that are not listed
Import music and playlists from your iPod even if it isn't associated with the computer running
SuperSync
Tracks are flagged for further inspection with "possible duplicates", "file duplicate", "missing tags", etc.
Unique "Filter table" lets you quickly find or hide tracks by type, flag, or playlist
Two-way synchronization lets you add music to your library or the library you're connected to
All available metadata (Star rating, played counts, grouping, comments, EQ settings, volume adjustment, etc.) are copied
Automatic router setup (UPnP) makes accessing your home library over the WAN even easier
Transfers your music up to 5x faster with simultaneous transfers and other optimizations
Unicode, long file name, and cross-platform filename support
New File Transfer window shows you exactly what files are transferring and the progress
Support for all media types supported by iTunes, and even those not officially supported, such as ogg
Tivo media server included to let you access and play your mp3's from your TV
Available in multi-packs for as low as $5/copy.
