Tonelib JAM is a software for creating, editing, printing and listening to tablature and sheet music for guitar and other fretted instruments. You can use Tonelib JAM for regular guitar practicing, for learning songs or for advancing your performance skills to the next level. The Tonelib JAM makes it easy to create backing tracks from just about any song. The internal player lets you change the playback tempo while keeping the same pitch and has facilities to loop a section of the music.
It's free and it worked for me with no hassles. Seems pretty cool.
I was using tuxguitar before (and also checked GP6 for linux and musescore) but wasn't really pleased by the usability and the jack capabilities.
Tonelib Jam is pretty cool and makes it easier for me to work on new songs, although the license is a little odd. I hope it stays free or will be OSS some day