Impro-Visor is a music notation and playback tool for helping jazz musicians learn to improvise. It features a notation GUI, automated playback of chords and rhythm using MIDI, and improvisation advice provided in a variety of ways, including being able to improvise jazz itself. Data are stored as open-format text files. MIDI and MusicXML export are also available.
Information regarding Project Releases and Project Resources. Note that the information here is a quote from Freecode.com page, and the downloads themselves may not be hosted on OSDN.