I'd go with the http://<state>.metal-shows.us or ~.com
The dash makes the name easier to read - that way you'll never get confused with "MetAlsHows.com" - or maybe that's just me.
You should make it so that people have to register for free to post shows, and ask them for basic info about promoters and venues (location, email, myspace, address). That would really help bands book DIY tours