Are you playing an instrument? Have you thought about composing music yourself, but found it too tedious to write down the scores and edit them? There are several highly advanced free software tools available for your Linux system that make this process much easier, and enable anybody to produce professionally looking music scores.

LilyPond is a nice piece of software not only for writing music, but also for learning music and music notation, if you follow the documenation. You can write music in plain text and LilyPond will output it in beautiful notation as PDF, PostScript, or TeX files. It is primarily a music typesetter for Linux, but it can also generate MIDI files that allow you to actually hear your compositions with the instruments you select.

Alternatively you can use Noteedit, a tool for writing and editing scores in a graphical user interface. It includes numerous features, such as specification of MIDI instruments and polyphony. Lyrics, chord markings and guitar diagrams are supported as well. Noteedit can export to various formats, including LilyPond and MIDI.

Rosegarden is another great music composition tool for Linux. In includes an advanced audio and MIDI sequencer.