For years, the Austinist staff has fielded queries from friends and acquaintances about SXSW goings-on. "Can I walk to The Salt Lick?" "Does it really take 90 minutes for a Casino El Camino burger?" But most of all: "What showcase do you recommend to see some good new bands I don't know about?" This year, we've made the answer official. Austinist is presenting an official nighttime showcase featuring six different American acts at Spiro's on Thursday, March 13. We've done a lot of listening to different bands and entire showcases, and believe that this one has great potential to impress you. The roster:...