Two students from London's Royal College of Art have come up with a recycled paper helmet. Dubbed the Paper Pulp Helmet is made from recycled newspaper, which is pulped and then combined with an organic additive to make the helmet water-resistant; the designers say that it's good for six to eight hours in the rain. The helmet is claimed to cost around 1 Pound, and is targeted for bike rental and bike hire schemes.
I like the idea, but I'm disappointed not to see any mention of how safe this helmet actually is, though I am sure they do plan to test it. It also seems like there is quite a lot of energy used to manufacture the helmet.
Its a great idea though, and I'd love to see a more refined version targeted at long term usage.