Here's an interesting article by Shawn Wildermuth:
Streaming with Windows Media Services and ASP.NET
It shows you how to setup the Windows Media Services SDK on IIS, create a web site to browse a collection of MP3s on disk, create a playlist, and then stream it to the user's computer! Tres cool.
I did something similar with RealPlayer and Cold Fusion back in the day that allowed the people in the repair lab to upload MP3s (hey, it was back in the days of Napster) and then stream short playlists over the intranet. But it wasn't this cool, and RealPlayer sucked back then. The more things change, the more they stay the same. :)