1)   Chord Miner 1.0.2
Manage chords and chord sets with this superb reference and repertoire tool from the publishers of Guitar and Keyboard Coach. See, hear, print and save the chords you do know, identify the ones you don't, then check out which songs use them.

 2)   Guitar Power - PalmOS Edition 1.1.0
The Ultimate Scale, Chord and Arpeggio Reference for Guitarists. Guitar Power is an interactive learning system. Quickly and easily use scales, chords and arpeggios. Any style or level - learn the secrets of the pros and play like your guitar heroes.

 3)   Chords 1.1
Find alternative fingerings any chord, identify unknown chords, make up and play new chords, and copy, save or print chord diagrams. Tune your guitar with the Guitar Tuner tool.