eh- for your head, you don't need to distribute force, like you would with other parts of the body. your skull does a pretty good job of that.
You need to give yourself some more time to decelerate, so your brain doesn't go slapping around inside your skull. Unfortunatly, barring some force-field style tech advance, you can't buy deceleration time without a big, dorky helmet. The more foam you have to crunch through on the way to the pavement, the better.

If you're too cool to wear a helmet, then that hat might be better than nothing come crashtime, i guess.