Musicians seem drawn to using public transit systems as a backdrop for performances. We've seen many a street rat busking in NYC and D.C. subways while strumming their acoustic gee-tars. Maybe it's the captive audience or Americana's deep-rooted bonds shared by trains and tunes. Either way, we figured that once the Valley's light-rail system launched last December, it wouldn't be too long until we heard live music at stations. The folks behind the Train Tracks did us one better and have been booking Phoenix indie acts to play unplugged versions of their songs on light-rail cars since February. Conjured up by a cabal of CenPho left-brain types (including Inside Creative Minds filmmaker Tray Goodman and Modified Arts/Stinkweeds' Kimber Lanning) the weekly online video series records acoustic performances by such local scene favorites as Courtney Marie Andrews, Yourchestra, and Sugar Thieves during rush hour. It's similar to London's Black Cab Sessions (albeit not in a back of a taxi), in which everything's done in one take. Every three months, those who get the best response are invited to compete in a quarterly First Friday battle of the bands at the Phoenix Art Museum. The winner will get stage time at next year's Tempe Musical Festival. Sounds good to us, as long as they don't ask us for spare change.