Not just a superb guitar player and mainstay of John Scofield’s Uberjam band, Avi Bortnik is an app developer. His metronome app, Time Guru, is designed to improve your time by gradually removing the crutch of its own beats, while his delay app, Echo Pitch, offers some new twists on an old theme. Voxbeat allows you to create drum patterns using your voice and phone. Check them out. Sorry this took so long Avi.
I swear by Time Guru!