Ishkur's Guide to Electronic Music 2.0 owns completely. After I play with this some more I'll post some recommended things to check out.
I was stupidly in a hurry to get this posted. Anyway, it's a Flash toy that lets you click on various genres and subgenres of electronica to listen to samples of each (between 4-8 songs are posted for each one). Along with each set of samples is a Maddox-esque description of each genre to tell you how it evolved within the electronica world. Oh, and they're spread out along a circular decade grid, so you can see when your favorites really came about. Surprisingly, most of the stuff I like originated about 5 years before I thought it did. There is a TON of music on here, so be sure to play around with it.