i didn't see a thread on this tracker, so i thought i'd add it. I've got basically 20 minutes experience with it, but it's a windows AtariXE/XL tracker for writing .SAP files. Capable of writing 4 tracks in mono or 8 tracks in stereo.
http://raster.infos.cz/atari/rmt/rmt.htm
This demo track that came with it is the reason i'm starting to learn RMT:
Caruso - 4tk32.mp3
http://dl.dropbox.com/u/6320154/Caruso%20-%204tk32.mp3