I wrote an application called FretBoard which runs on the iPhone and the iPod Touch.
With this application you can easily learn the position of notes, scales and chords on virtually any stringed instrument. This application currently supports 105 instrument tunings, including 6 Warr guitar tunings. There are also tunings for Guitar, Banjo, Bouzouki, Bass (4, 5 and 6 string), Dobro, Charango, Lap
Steel and Pedal Steel, Mandolin, Violin, Viola, Cello, Lute, Viola da
gamba, Ukulele, Dulcimer and some other instruments.
I tried to make the application as easy as possible, although it includes an immense amount of theory in a database of 55 chords and 58 scales that you can display in any key on the fretboard.
There is also a free version called "FretBoard LE" if you like to try this application before you spent money on it.
And here comes the fun part:Only for this weekend I reduced the price of FretBoard by 50%, so if you like this application, now is the time to grab it...
Best, TheMM
PS: If you are missing a special tuning, just let me know. I'm happy to include it in one of the next versions...