Looks like the material inside a cheap simple bean bag is more than enough when it comes to protecting your head. Vaco12 has used bean bag beans to make an innovative padding technology.
The foam linings in a helmet have been effective at absorbing shock for years now, but it turns out bean bags are better at it since the forces can be transferred from bean to bean across a larger area. Vaco12's system uses a small polypropylene beads that make each of them contact with one another up to 12 other beads so that energy is transferred along the way as it is dispersed and weakened again. Which ultimately gives you less chance of an injury when absorbing an impact.