XMMS-fc is a plugin for XMMS and supports the Future Composer format.
One caveat: please don't submit any damaged files or try to play well-known FC modules like Astaroth or Chambers of Shaolin from beginning to end. These modules contain several independent sub-songs that should be played separately. Luckily, prepared versions of these sub-songs are available for download on the page below. You can safely delete your old all-in-one version of Astaroth, as it's meant to be used exclusively in the original game. This is in contrast to what the documentation files for Future Composer might say.
All in all, if you're an FC fan and an XMMS user, xmms-fc is a must-have plugin that will reliably play back your favorite modules with ease.
Version 0.5.4: N/A