The MotoGP guys have a system in their leathers that inflates, then if they pick the bike up and toss it into the scenery again, it has a second charge so they have protection again as well. They use what looks like a CO2 cylinder from a bicycle tire inflation kit (the type with a threaded top as opposed to the BB/Pelet gun style) and it tucks into the aero-hump on the back.
The vest is a similar system, but really one charge should be plenty... Also, the racing system doesn't inflate nearly as much, but is more as added padding to the clavicle area and doesn't limit the head quite as much. I too have seen the other one that is HIT. Best thing is all of them are rechargeable/repackable and the teather ones are very simple designs.
I'd consider one built into a jacket.