Meet the Roadie 3: an automatic instrument tuner that uses a 120RPM motor to get your string instrument into perfect tune. It is pretty easy to use too. Simply select your tuning, place Roadie on the peg, and watch it do the work.
Roadie 3 can tune anything with geared pegs, including electric/acoustic guitars, ukuleles, banjos, and mandolins. It has a full color high resolution screen and an app to make your life easier. The device ships with 100+ turnings but you can save your own custom ones.