Have you heard about this invention called the "Invisible Bike Helmet"? Two women in Sweden came up with it. Instead of putting a helmet on, you strap something around your neck. Then if you fall, it senses the impact and deploys an airbag that goes around your ENTIRE HEAD. It's getting some attention now because G.E. released a video about it. You can check it out, but you have to skip to the three-minute mark to see it in action.
--Or you can watch the raw crash-test footage that they posted on YouTube in 2010 right here.