If you're talking music Abney Park (http://www.myspace.com/abneypark) is the most noticed steampunk band, I believe. There are several others who fall into that specific genre like The Extraordinary Contraptions (http://www.myspace.com/theextraordinarycontraptions), Steam Powered Giraffe (http://www.myspace.com/steampoweredgiraffe), and The Clockwork Quartet (http://www.myspace.com/theclockworkquartet). There's also a lot of music that is embraced by the steampunk scene that is not overtly steampunk, but is very retro-futuristic in nature and therefore fits in with the anachronism of it all. Also, they're just rad. You can find a collection of some of those here (http://retrofuturistique.tumblr.com/).