Pro Metronome iOS Free Metronome
Tonal Energy iOS - $3.99 - This app offers equal and just temperament tuning, tone wheel, piano, guitar, recording, sharing of recording, recording manipulation, spectrometer, amplitude graphics and ...too much to write here. Get this for a fantastic tuner and metronome combo.
Staff Wars for Desktops - Free!
The Band Tool Box iOS - $.99 - Tuner, metronome, vocabulary definitions and fingerings.