Mariachi-rockers Calexico may be headlining tonight, but the bill's more riveting act is the Cave Singers. It's hard to convincingly evoke shotgun-shack folk in 2008—especially for Seattle sophisticates like the Cave Singers. But their rickety shuffle, stark arrangements, inbred-goat vocals, and irresistible, serious-as-rotgut tunes transport you to a much more humid and thrillingly scary place than a classy old venue in downtown Seattle. Clap your feet and stomp your hands, y'all. (Moore Theatre, 1932 Second Ave, 628-0888. 8 pm, $20, all ages.)