DJing on Linux is an interesting topic, most audio servers are ran on Linux systems, but DJing tools and applications are far and few in between. One tool I stumbled upon recently was the Internet DJ Console. The IDJC has many popular features such as multiple playlists, microphone voice over and a "tracks played" listing, but lacks a music library. Compared to popular DJing applications such as Winamp and SAM Broadcaster, it falls in the middle. The Internet DJ Console only works with MP3’s, and from my informal testing a pretty solid program. I only recommend this app for experienced users, as installation is not easy. For hardcore Linux users, this is a program worth spending time with!
To download the program and gather more information, visit: http://www.onlymeok.nildram.co.uk
Here's an article I refer to sometimes regarding Linux and Streaming: http://www.linuxdevcenter.com/pub/a/linux/2001/03…
IDJC works pretty well, but it tends to monopolize audio on Linux by default using JACK, preventing one from hearing any other system or application sounds like SL's own sounds. There's a way around that, here:
http://www.aukondk.com/blog/?p=115
It can use the following files ogg, oga, wav, aiff, au, avi, wma, ape, mpc, mp4, m4a, m4b, m4p, flac, spx, mp3, which it streams out as either ogg or mp3. So you can feed it flac, and send out mp3. Installation's easy, if it's in your distro's repos or you find an rpm. I think it's in Ubuntu's repos but it's not in the standard Fedora repos, not even RPMfusion, but you can get an rpm of the 0.8.1 version here:
http://fenris02.fedorapeople.org/
Easy enough to compile from source, if you have the dependencies, though 64 bit users will have to symlink /usr/local/lib/python-2.6 to /usr/local/lib64/python-2.6
As you said, functionality wise it's probably in between SAM and the winamp plugin, which is actually a good thing in my book.