You might want to call ahead before lugging your gear down to the 13th Street Workshop, Monday nights at Tulagi in Boulder, or face the possibility of lugging it right back home untouched. Since its inception earlier in the year, the weekly open-stage event has maintained a buzz that Tommy Chong would kill for. And while its popularity means that stage time is somewhat hard to come by (hopeful acts should phone 303-310-1033 a few weeks in advance), it has also made for more interesting offerings. Bands and solo performers of all styles have navigated the unregulated musical terrain inside the smallish club adjoining the Fox Theatre, and participants have occasionally been inspired to end the evening with all-inclusive freewheeling jams. So come prepared to listen to some new sounds -- and possibly add a few of your own.