Music Education and Practice Aides
Artusi Music
An excellent (and free) online music theory course. This is used in schools and universities.
Tonal Energy App
An all-in-one practice tool that includes a metronome, tuner, pitch generator, and much more! This is a paid app, but it is well worth it.
10 Tips for Effective Practice
These are 10 easy ways you can optimize your practice time.
Good-ear.com
Very helpful site for ear training. Includes intervals, chords, scales, cadences, and more.
Flash Music Games
Great online music theory games. Good for personal study or classes. Includes notes, piano games, kids content, and more!