I saw a video of the "Guts" of a model S lately, and I noticed 2 points about the battery:
-It is a 4 inch slab, I believe integral part of the car structure
-It is connected to some sort of heat exchangers at the front of the car
Others have suggested putting two of these slabs under the car for extended range, and the model S has air suspension, which made me think:
How about interchangeable, stackable batteries? Obviously you'd want something a bit more sophisticated than electric forklift-style tech:
I'm imagining some sort of serrated, multi-hook attaching system with a countercurrent or heat-pipe heat exchanging system.
If you want more range, you just strap on another battery, while eliminating the need of hauling a heavy high-range battery on your daily commute.
An air suspension system should be able to accommodate the height and handling differences (riding 4 inches higher with 2 batteries, I presume) The whole combined with containerized automated battery changing stations, perhaps with a pallet-jack-style system for changing the range of your EV at home.
Now of course, battery exchange is not at all new, but seeing that flat slab made me think "Hey, this could be standardized".
I believe that the whole idea of having massive range on an EV is comforting, but usually unnecessary and detrimental to efficiency and performance; since we are in the information age, it would be entirely possible to have a reservation system for batteries. That big 17' screen could show where the next battery is, how full it is and let you reserve it.
Setting standard length, width and a mechanical, electric and thermal interface for exchangeable batteries would be a huge step forward, and would greatly benefit the company setting the standard.