I recently read on absence of XMMS in the Ubuntu repositories.
I noticed a while ago that XMMS development seems to be stuck somehow and the Debian repositories weren’t up-to-date. There is the XMMS 2 project, but at the time I was looking for an alternative of XMMS it wasn’t at a usable state.
Therefore I came to the very same choice as schmalenegger and decided to go for Audacious. We had our problems in the very beginning of our relationship, but now we work together very well.