Really, stop going on about tyre adhesion - it doesn't come into play unless you are skidding.
The braking system on a car is for transfer of energy into heat, and this is mainly done by the friction of the dics/pads, not the tryes/road surface.
If it was solely tyre adhesion then all F1 cars would have the same discs as my mum's metro and the same stopping distances.
Huge, drilled and ventilated top quality discs will provide you with a better stopping distance than small cheap ones because they are vastly superior at transferring all that kinetic into heat and more importantly, at dispersing that heat away from themselves.
Anyway, in a modern car it would be very rare to reach the tyre adhesion limits (around 1.2-1.7g) as the ABS will kick in to keep the wheel rolling (and the energy transfer at its maximum).
MHO on the current ideas:
The retro rocket idea would help with energy transfer, but I would doubt that you could get anything solid fuelled to fire in the time required (or stop when you needed it to) and would probably be a bit on the dangerous side.
Traits of drivers thing has already been done - think Volvo had a thing that flashed the hazard lights if you took your foot off the accelerator very rapidly. Didn't apply the brakes but I would be surprised if they didn't patent the idea.
Aerodynamic braking has promise, but only at higher speeds (the surface area needed for any reasonable effect at low speed would be huge)
The old inverse square law could be a bit of a sod too - the correct area to provide super stopping at 60mph would punch the occupants (seats included) through the windscreen at 100mph!
Flywheel thing would take so much energy to get it spinning that the MPG would be through the roof. It might also have a wierd gyroscopic effect that would decrease cornering forces if big enough.
Extra rubber might help if it all goes wrong and you end up skidding - top fuel dragsters can manage 3.0g tyre adhesion under acceleration, so bung some dragster tyres on and maybe your sorted.