MuseScore | Free music composition & notation software

MuseScore is a free cross platform WYSIWYG music notation program, licenced under GNU GPL. It imports/exports MusicXML & Standard MIDI files and it's free - worth checking out if you can't afford or don't want to use Finale or Sibelius, the industry standard notation programs (both of which can save files in MusicXML format). I might check it out myself.