The AFMM produces and commissions works which use pitches and musical scales which are not organized in the standard twelve tone to the octave equally tempered way.

Microtonal instruments, recordings and books.

Microtonal music page with large list of composers, mp3, WAV, MIDI, and Real Audio files of microtonal music.

Excellent discography of microtonal / xenharmonic / non-12 tone music (CD only). Contains addresses for record labels, and links to the artists (when available).

LucyTuning is a microtonal system derived from pi, and the writings of John 'Longitude' Harrison.

Argues that the 34-tone equal-temperament scale is the most "natural" equal-temperament scale with fewer than 53 tones.

Notes on microtonal composition, with sound files and an introduction to the 43 tone scale.