We recently assembled a bike for an MIT student, Yang. A couple days later she came back with the above prototype LED signal arrow. It’s a removable backpack attachment with LED arrows, each on their own circuit, with activation buttons placed on the backpack’s shoulder strap. This solves the problem of bicycle turn signaling: most cyclists either don’t know proper signaling, don’t use signals, or make up their own hand gestures to signal where they’re going. She’s got a lot of bright ideas floating around. To see more of them, check out her blog; YangWare.