Mastodon, 'Crack the Skye'

The buzz: Grammy nominations, album of the year accolades, veterans of both the Bonnaroo Music Festival and Slayer tours, Mastodon is the rare metal band to nab mainstream acceptance along with indie rock cred. On the group's fourth record, the guys thankfully eschew any ideas of destroying this built-up goodwill; instead, they actually get a little weirder and proggier, even under the tuteledge of noted alt-rock producer Brendan O'Brien (Pearl Jam, Bruce Springsteen).

The verdict: Six- to 10-minute songs about etheral worlds, Rasputin and galactic wormholes do not portend the next coming of Metallica (the suckier, radio-friendly era). Instead, Mastodon create ominous, midtempo jams, rarely delving into thrash and keeping the vocals of Troy Sanders and Brent Hinds far from scream/Cookie Monster territory. Actually, the 10-minute "The Czar," complete with weird sci-fi keyboards and freakout guitar solos, is essentially a perfect melding of progressive metal and Pink Floyd—it's possibly the band's crowning moment. Just don't go listening for it on the radio.

Did you know? Heavy metal makes for awesome videos. The clip for this LP's first single, "Divinations," features guitarist/vocalist Hinds as a frozen cavemen who is rescued from his frozen state by his bandmates (as arctic explorers) using the power of an ice-melting guitar. As Hinds explained in a recent interview: "I then grab the guitar, do the solo and then I kill [the band]."