
All this simple app does is detect the pitch of the built-in mic’s sound. A tone wheel spins to a position from A to G#, and a more precise meter on top shows how close to the perfect tuning you are.
Links:
[1] http://www.maclife.com/article/reviews/cleartune
[2] http://www.maclife.com/article/guitar_rig_2_software_edition
[3] http://www.maclife.com/article/iplaymusic_beginner_guitar_lessons_and_play_music_together
[4] http://www.maclife.com/article/optek_music_systems_fretlight_fg_431_vintage_electric_guitar
[5] http://www.bitcount.com/cleartune/