Fractal Tune Smithy Description:

Create beautiful music effortlessly - and discover your talent as a budding composer! Choose one of the tunes that come with the program or enter a very short musical phrase of a few notes, and hear it transformed into an intricate tracery of music. The music is fractal which means it is highly structured, but natural sounding too, like bird song, or the sound of the wind. Any tuning is possible; no need to restrict your creativity to the equal tempered twelve tone system or even the octave. Tune your music as freely as a bird when it sings. Try authentic historical temperaments with tunings for keyboards from Bach or Mozart's time. Try tunings for Indonesian Gamelans, or Indian music with drones. Try modern exotic tunings such as non octave scales, or musical geometries with highly symmetrical floating chord patterns. Explore the effects of instrumentation, and take ones first steps as a composer in an envionment where melody making is effortless. Suitable even for complete newbies to composing - and there is no need to be able to read music notation. Play in any of the tunings and temperaments yourself with a music keyboard. Even play melodies and chords on the p.c. keyboard - with the space bar as a sustain pedal, and the mouse scroll wheel as a modulation wheel :-). Play legato style (if your synth supports it) in microtonal tunings as readily as you do in twelve equal. What else - make fibonacci rhythms which are highly structured, but never repeat exactly. Make polyrhythm metronomes. A mouse theremin which can play sliding chords as well as single notes. Send your tunes to your friends as musical e-cards. Over a megabyte of help, tutorials, FAQ, example midi clips and tunes, etc.

It is freeware / shareware - use it as it is with some limitations.
Or buy at a very affordable price to hear your own tunes continue endlessly. You can also start a 30 day trial at any time to try it as it is unlocked, for free.