Sharing iTunes between computers
From Mac Guides
iTunes 4 and later allow music streaming between iTunes on different computers. It is useful if you use one computer as a music server, or want to share your music between people (for example in a college flat). It only works with local users and not over the internet, and only allows 5 people to listen to your music each day. It allows streaming music between Windows and Mac users.
- Open iTunes' preferences (iTunes > Preferences in Mac OS X, Edit > Preferences in Windows).
- Select the Sharing pane. Tick the Share My Music option, if not already on. Configure below whether you only want to share specific playlists or your whole library.