Here's a trailer for "Line of Sight," a documentary on underground bike-messenger racing that uses helmetcams to capture some pretty insane (and often terrifying) examples of cycling skill:
Line Of Sight is a rare view into underground bicycle messenger racing which has become a global phenomenon. For over a decade Lucas Brunelle has been riding with the fastest, most skilled urban cyclists around the world while capturing all the action with his customized helmet cameras to bring you along for the ride.
This is bike riding like you've never seen before, in gripping first-person perspective through the most hectic city streets, on expressways in Mexico City, over the frozen Charles River, under the Mediterranean Sea, across the Great Wall of China and deep into the jungles of Guatemala.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.