A site dedicated to making Music with Macs.
This guy has some great software...
EarTraining, GuitarPaper, Metronome, StudioLog, Maestro, GuitarTuner
FretPet is an award-winning guitar-oriented 4-track music sequencer with a genuinely unique interface that makes writing music easy and fun. It contains a variety of palettes that showcase many different aspects of your notes, chords, and scales. (It's not OS X native, unfortunately, but should run in Classic.)
ChordBook v2.6 provides chord lookup for guitar in standard tuning, and additional chord processing for 70 non-standard guitar tunings. ChordBook's purpose is simple--provide a way to create your own, customized chord listings....in the order and with the voicing YOU choose.
GuitarTab is a guitar tabulature program for the macintosh, by Greg Clayton, which allows easy guitar tablature editing, graphical display and playback. GuitarTab is fully carbonized so it runs on and Macintosh system running MacOS8 up to and including MacOSX.
MetroGnome is a highly customizable freeware metronome for OS X (Cocoa), featuring many time signatures (2/4, 3/4, 4/4, 5/8, 6/8, 7/8, and 12/
, volume control, mutes, accents, customizable sounds, silence, and tap entry.
Sorry if any of these are duplicates... i didn't feel like double-checking them all against the versiontracker links.