This website is awesome. It's like a family tree of electronic music with GOOD examples of each genre.
This tells you all about electronic music and its origins including hip-hop, turntablism, drum and bass, hardcore techno, trance, house, EVERYTHING. You WILL find some very interesting history.
If you ever feel like you can't find enough music, check this out. Find something that you think sounds good. Explore.
The person who made this has also written his opinion on almost every genre. I think I can agree with everything he said.