The Bag Bright is a cool messenger bag concept that I came up with back in 2007. I built this prototype using the Nite Dawg LED Dog Leash it is made by Nite Ize out of Boulder, CO. The prototype works great and can be seen from quite a distance. The LED module has two different modes, solid or blinking which can help with visibility.
The flexible polymer that the LED module lights up is nice because it can bend with the fabric of the messenger bag. This type of lighting system could easily be integrated with a backpack or worn as a belt too.