From Harmonic Sense:
ChordMate is a software program for songwriters, guitar players, guitar teachers and guitar students. It helps you find the right chords and arrange them into beautiful chord progressions.
Choose from the chords that matter. Organize chords by their musical quality, by ease of play, or by fret. In most cases, your perfect chord will be one of the first that we show.
Put chords together to create beautiful chord progressions.
Listen to how the different voicings sound on your computer. You can even play an entire chord progression!
Drag-and-drop chord diagrams directly into Mail or TextEdit.