Fine Tuner is a minimalistic tuner with a user interface optimized for guitar, bass, violin, ukulele, banjo and other string instruments. It utilizes your device's built-in microphone. The app includes over 30 popular guitar tunings as well as several tunings for a variety of other instruments. Fine Tuner also has the ability to tune to a custom note and can be used to tune almost any instrument.
The free version of the app includes standard guitar, drop d, and double drop d tunings.