Today I stumbled upon http://liveplasma.com/, a site that allows you to type in the name of an artist and have an interactive visual map created for you that encapsulates the band's sound and situates them spatially with other bands that share common traits. I made a map of one of my favorites, Mastodon, and it came out looking like this: http://liveplasma.com/index.php?data=234099&datatype=artis&ct=us&idmsg=5161
You can then click on the bubble of any related artist and it'll regenerate a new map for that band, allowing you to find related bands pretty easily and in a way that is easy to process. As opposed to sites like Pandora and Last.fm that play songs you might like on a streaming basis, liveplasma allows you to pick and choose which artists look like they'd fit best with your interests and then go sample their stuff elsewhere. I recommend Grooveshark or, you know, youtube.
My only complaint is that the search doesn't appear to be very deep, which is to say that a lot of smaller or less-known bands seem to have been omitted from liveplasma's application. Even so, it's worth checking out and provides a distraction from work or whatever else you don't care to be dealing with.
Cheers, and happy hunting.