Imagine a Twin Cities open mic where the likes of Jeremy Messersmith, Aby Wolf, and Lucy Michelle stopped in weekly to debut new songs, and which occasionally played host to stars like Brother Ali, Bob Mould, or even His Purple Eminence. The standup comedy equivalent of this improbably stacked show takes place every Monday at Acme, where some of the best up-and-coming comedians in the country go to work out new jokes and hone their acts, and where surprise out-of-town guests are always a possibility. Acme's impressive roster of in-house comedians includes several nationally touring performers, and its alumni, who stop in regularly, have appeared at the Montreal and Aspen comedy festivals, on Comedy Central, and on late-night talk shows. The club does a sharp job of balancing the list to include a few brave first-timers, a handful of aspiring jokesters, and a cadre of polished pros. It's the best free show in town, and an excellent sampler of the Twin Cities comedy scene.