Check out these awesome cardboard crash helmets from Kranium.  What an awesome idea!  it turns out the corrugated paper product actually makes a better impact absorber than polystyrene.

Kranium technology uses interlocking ribs made from cardboard housed under a stiff plastic shell. Since the cardboard is easily manufactured and cut to shape, custom fitment is possible by means of a simple and personalized head-shaped template. This way, the guts can be cut out of a single cardboard sheet and replaced without buying a completely new helmet.

Tests show that these cardboard helmets can withstand four times more impact energy than regular helmets. Just as interestingly, while polystyrene helmets can only take a single impact, these Kranium helmets can reportedly pass testing after five strikes. Read more about the technology at the Kranium site.