Innovation
Here's a couple innovative online music radio ideas:
http://www.pandora.com
Called the music genome project (clever), you enter an artist or song that you like, and it creates a station based on that. From there it chooses songs that it thinks you'd like, and even tells you why, lol. You can provide further feedback on whether you liked its choices and it'll adapt.
http://www.musicovery.com/
A focus on discovering music - you can choose two categories, Ambience or Dance, and choose options within there. The neat mapping it provides is cool. You can specify the decades that you'd want the radio to play from, or just choose the genre from the bottom of the "remote" there. Neat things include specifying mood (energetic, calm, positive, or dark) and increasing or decreasing desired tempo.
Enjoy ;)
Other interesting links I've come across are always posted up on my links page: www.allantan.net/links, served up by http://del.icio.us/.