Tips to Learn Music Scales in 2 Minutes - Tipsographic
Understanding guitar chords, not that I actually need it anymore, but maybe I'll forget someday.
MAN, I could've used this when I was little and taking piano lessons. A basic discussion of scales and chords.
Music Theory Cheat Sheet, aka "Write Awesome Music In 5 Minutes" (it's basically a guide to the most common rock/pop chord progressions and how to play them in any key)