MuseScore looks like fun if you’re musically inclined. It’s a free, and open-source, music notation program that lets you create detailed sheet music easily. It’s WYSIWYG and you can enter your music using either a mouse, computer keyboard or MIDI. It has automatic note head positioning for laying out chords, you can add drum notation and cross staff beams. It’s also available in 20 languages and works with Windows, Linux and Mac.
MuseScore is a free cross platform WYSIWYG music notation program, licenced under GNU GPL. / WYSIWYG, notes are entered on a “virtual note sheet” / Unlimited number of staves / Up to four voices per staff / Easy and fast note entry with mouse, keyboard or MIDI