Fretter - Chordfinder (Android) app for $0.99

Fretter is an advanced chord finder. It doesn't rely on a database with diagrams; instead, it calculates all the possible diagrams for a given chord/instrument/tuning combination. The app's algorithm is optimized to present only the chords that you can actually play. Select any tuning, including custom ones, and still get all the possible chords presented to you.+