Longevity for music clubs in this city is akin to "dog years." A decade run equals a lifetime anywhere else. Which means the biweekly open-mike night at Luna Star Café, now in its eighth year, has grown long in the tooth. But you'd never notice by the exuberance of the participants, a roster of volunteer songsters who begin signing up about 8:00 p.m. for a night that runs into the wee hours. Young guns getting their first taste of the spotlight and old folkies reliving their glory days take to the stage with guitars, keyboards, even an occasional banjo or bongo. And it's not just one and done. Players can settle in and show their stuff with a set of three or four tunes. Neither is the night relegated to a slow Tuesday, like so many such affairs. Luna's jam takes place on Saturdays. Bring your six-string and work those vocals for the faithful, then relax with a few cold ones in Luna Star's friendly, casual, and arty atmosphere.