TunesAtWork lets you listen to your personal iTunes music collection while at your office or lab, even though your iTunes collection resides at home.
TunesAtWork is a specialized web server that runs on your home Macintosh and serves web pages that present your music collection (including playlists) organized visually much the same as in iTunes itself. This makes it easy to find what you’re looking for.
Clicking the various links in the web page will cause MP3 files to be streamed from your home Mac to the computer where your browser is running. As long as that computer (where the browser is running) has a helper application that can play streamed MP3 files (e.g., WinAmp on Windows, MacAmp or iTunes itself on Macintosh), you will hear your music on that computer.
TunesAtWork is free. It requires a Mac, OS X, iTunes 4, and a high-speed internet connection. More info and download link here.