AWS Guitar Tuner is a simple and free nonchromatic tuner. Offers standard and alternative tunings and a three-octave noteplayer.
Version 2: Now has nine alternative tunings including DADGAD/Celtic, open tunings, Double Drop D, and more. Users can now tune online without downloading the software. Also makes available supplemental MP3/AAC "Digital Pitch Pipes" for tuning via iPod or other MP3-playing device.
Mac OS X 10.1 or later