There is no better way to learn electronics and become a pro maker than building your own things. Arduino is a wonderful platform that you can rely on to make your own interactive jacket for cycling. mujtabachang has shared a guide that shows you how to do just that. The jacket has turn signals that can be activated by using simple hand gestures.
This Interactive Cycling Jacket also comes with front and back LEDs to keep you visible. You are going to need an Arduino UNO or LilyPad, two accelerometers, LED lights, and a few other components to complete this project. More info is available on Instructables.