There are plenty of cool smart cycling backpacks available on the market these days. Bike riders can use them to stay visible. Care to build your own smart backpack? You may want to try the Arduibag. This open source project involves building a backpack that shows a flashing arrow to show which direction you are going. You can also display messages and information like time, temperature, and humidity on the backpack.
Arduibag simply keeps you visible on the road. Why buy when you can build one yourself?