See this bike helmet? No? That's because it's invisible. No, really, it is: that hefty collar that the bicyclist (or whatever) in the above pic is wearing contains a helmet-shaped airbag that deploys on demand to save your skull, and spends the rest of its time out of the way and looking fashionable.
The Hövding (that's "chieftain" in Swedish) took seven years and $10 million to bring from concept to product, but unlike most things that are invisible, it's finally out there for purchase: you can buy a Hövding of your very own for just four of these bad boys:
That works out to about 4,000 Swedish kronor, which sounds like a lot, and equates to just under $600 USD, which also sounds like a lot. But remember, you're not paying for a helmet, you're paying for lack of a helmet without compromising your safety. And also, you get a free neck warmer. So it's totally worth it. And if you're still not sold, there's a video of the Hövding in action below.