Ricci Adam's Musictheory.net lessons and interactive training

Above: Jelly Roll Morton. Music score for "London Blues." Chicago: Melrose Brothers, 1923.
Music Division, Library of Congress (236A)

I've been studying music theory again. I've always been interested in it, but remained bogged down somewhere between the circle of fifths and the mixolydian mode. I found a great site, Ricci Adam's Musictheory.net which has simple, clear, flash explanations of the basics like pitch, time signatures and scales. Even better, there are interactive apps you can practice with, like an interval ear trainer and a note trainer. I was really happy to find this because I started learning the theory faster than any other way I've tried. And no, this is not an ad for the site--it's free!