Jason over @ Hackszine shows you how to run an iTunes (DAAP) server in Linux with Firefly -
Firefly, formerly mt-daapd, is an open source digital audio server that can stream your music library to iTunes. Linux appears to be the most supported platform, but there is also beta support for Mac OS X, Windows, and even the AppleTV!
One of its cooler features is that it’s capable of transcoding your music files on-the-fly to a format that’s playable by your iTunes client. So if you’ve been building up a huge OGG or FLAC library, Firefly will let iTunes know that these songs are available and it will automatically convert them into a format that can be played on the client.