So the 6D helmet, which I'm sure you're aware of, is interesting.
http://www.6dhelmets.com
Instead of thick EPS it uses little elastomer (rubber, for you old-school geezers) bobbins, that suspend an inner EPS liner from an outer hard shell. The EPS is thinner than we're used to, so the outer shell remains the same size.
Link to original page on YouTube.
They were just awarded a patent on the technology.
What makes this interesting isn't that it absorbs energy any more effectively (although it might), but that it allows the helmet to do something a conventional one cannot. Namely, the shell can move laterally relative to the liner, in any direction.
So an impact that applies a twisting force to your neck (like having your face slide along the pavement) will transmit less of that force to your spine. The outer helmet will rotate but the inner one won't (as much).
Link to original page on YouTube.
As of right now, they only have a motocross and MX bike helmet. Will be interesting to see what they come up with for the rest of us... and also interesting to see what happens when SNELL, ECE and SHARP get their hands on it.