Oh i forgot my new favorite app... Guitar scp... Kinda like guitarist reference and chord app, just doesnt have a chord finder.. I like it for the keys, as i am a 16 yr guitarist whose primary goal today is learning music theory inside and out..

I think best apps i listed are guitar scp for scales, chord bank for chords, chord! For android... And seriously if you dont wnt to spend. Dime, that jguitar.com site doe it ALL for free!!