musescore: musescore (WYSIWYG music notation program)
musescore: 
musescore: MuseScore is a free cross platform WYSIWYG music notation program, 
musescore: licenced under GNU GPL. Some highlights:
musescore:  
musescore:   * WYSIWYG, notes are entered on a "virtual note sheet"
musescore:   * Unlimited number of staves
musescore:   * Up to four voices per staff
musescore:   * Easy and fast note entry with mouse, keyboard or MIDI
musescore:   * Integrated sequencer and FluidSynth software synthesizer
musescore:   * More, much more!