Mobile iTunes Library?
From TechCrunch:
Avvenu has a new product that allows you to listen to your iTunes music connection from any web browser on a Windows PC, Mac, or Windows Mobile 5 smartphone. MobileCrunch covered an early version of the product that only worked on Windows Mobile phones here.
The base computer storing the music must be a Windows PC. As long as that base PC is powered on and online, your entire iTunes music library will stream to the browser on the remote computer, and playlists will also be available. Avvenu also allows users to store up to 250 songs on their servers, allowing you to play those songs remotely without your base PC online (this is getting into a legal gray area).
This might be pretty easy to do with rTunes, maybe a possible new feature once I finish the Apple port.