Pandora is an automated music recommendation service and custodian of the Music Genome Project. Users enter a song or artist that they enjoy, and the service responds by playing selections that are musically similar
just type the name of a familiar electronic music composer, like Tiesto, etc. you will be amazed when finding new composers you didn't even know.
Is great, It's free (but you can upgrade it if you want to)
I find them very comprehensive, cover a lot of sub genera of electronic music.
My isp is a premium service provider so I also get di.fm in 256k without ads, so check if your isp have that. Its better quality then the free 96k, but if your isp don't stream 256k, 96k is still better than nothing.
Check the chiptunes channel as well, I recently get addicted to it.