Street festival season in Chicago could also be considered theatre festival season. The dog days of summer provide Chicagoans interested in adventurous new stage work with a plethora of opportunities. Last weekend saw the annual Stages set of new musicals at Theatre Building Chicago. Currently ongoing are Live Bait's Fillet of Solo fest of solo performance and Steppenwolf's new entry, the First Look Repertory of New Work. This weekend brings two more players to the table, with the two-week Single File collection of solo pieces, and the three-day tsunami of fringe theatre that is Abbie Hoffman Died For Our Sins. Go out and see something new.