One of my odder interests are impact and protection. Slashdot recently ran an article with someone advocating using basically a memory foam for hardening armor. Now, I don't have a sample of memory foam right now, but I've seen Silly Putty and high density water-corn starch concoctions flow and move at one time and act like steel at a different time. I think that professional systems for impact absorption (special sparring suits) use a Neoprene outer shell, EVA underlay and a high density memory foam core, and probably similar layering going out the other side.
Now, WHY am I suddenly interested in this?
I've always got my mind on using stuff I build or want to build. I often wander back to Airsoft or Paintball as test grounds and play fields. Paint ball especially can HURT, so people wear armor. Now, most is fairly hard, but what if a lighter weight, fully pliable material was possible? Because it's local hardening, it should give more warning that you've been hit while still keeping the impact down. I've had a line of balls fired down my midsection before, it knocked the breath out of me. I'd have loved to have an inch or two of soft armor between me and them. Airsoft, due to the lower delivered energy, doesn't need to worry about this unless 25mm canister rounds start flying.