You know you love metal. If you are a metalhead, you probably have genres and sub-genres you like. If you are a little more casual, then you probably like visual kei or classic rock or some related genre of metal. But I'm positive, just like there is someone out there that is right for you, there is a metal song that is right for you.
Map of Heavy Metal (flash required)
This will help you figure out what you like, what is related, maybe help you find something else that you like. And it will burn up a chunk of your day exploring. Use the minimap to move the big map around. Click on a genre and in many genres you can listen to a little sample.
Found one that does Techno music:
Electronic Music Map
Not as polished, but just as fun! I also think everyone loves Electronic music.