I did a short article for Personal Computer World (Christmas 2007 issue, just published) on how to use the Slimserver API from VB.NET. This example app is the result. It is sadly incomplete but could be a starting point for an app that controls Slimserver.
Why would you want to do this? Well, Slimserver has a good web UI but programmatic control is useful as well. One possibility would be to create a smart remote using a Windows Mobile device. Operating a Squeezebox using the supplied remote is fairly arduous. I also like the idea of a really capable rich client for Slimserver, with advanced search, playlist management and so on.
Just in case you don’t know Slimserver … it’s a great way to manage your music on a network. It’s free, cross-platform, understands lots of music formats including FLAC (my favourite), and supports multi-room playback using either the free Softsqueeze, a Java player, or the Squeezebox hardware. It can also transcode to an MP3 stream, so that all sorts of devices can play what’s on your Slimserver.