And I'd like to add, since Floyd Zepp and Deep Purple were already mentioned:

Kalmah and Amon Amarth--Viking metal!!
They're both melodic death metal bands, so they may not suit the tastes of any non-vikings, though they're very norse-mythical sounding, so I enjoy them.

Mastodon--my favorite band, progressive/sludge and a whole lotta other stuff, write only concept albums, amazing music and concepts like Melville's Moby Dick...new album coming out 24th of march, more stoner classic rock, can't wait!!

Gojira--been described as a French Mastodon, though sounds completely different...very heavy, interesting music.

Neurosis, Procupine Tree -- probably most people know, I really enjoy them though.

Opeth- a league above all other bands, simply amazing.