It's less of a Showtime at the Apollo for suburban would-bes than a genuine hootenanny at this downtown St. Paul stalwart. The Artists' Quarter is a beatnik's pleasure dome, albeit the type of place Sal Paradise might've been booted from for lollygagging (eight minutes, please). The AQ's habituÈs arrive armed with acoustic guitars, a few good jokes, and Saul Williams's salty palette. Underground, the people are genuine. They'll clap instead of snapping their fingers per an early San Francisco slam. Monday night's usual packed house still allows the performer plenty of room, and warmth, to trip over the peripheral lines of experimentation.