Here’s SEIL Bag, a Red Dot Design Award 2010 winner by Lee Myung Su Design Lab. SEIL stands for Safe Enjoy Interact Light and it’s basically a backpack equipped with an integrated LED display which you can control via a small, wireless remote. Now, this helps you easily interact with people behind you when you bicycle in traffic such as turn left/right, stop and so on. If there’s no turns or stops you want to communicate you can always have it show animated, happy emoticons, of course.
See it in action here: