Actually, a few 'spy' shops do sell a security system like what James Bond had on his 750il (hmmm... even James Bond can't stop jeolous vandals!)
It's basically a souped up stun gun wired to the bodyshell of the car... although a more common setup is wired to the door handles.
I lost the link when my PC crashed a few months ago, but I remember the price tag was something like US$7000 or so for the basic kit.
The other system is to prevent car jacking. It's available in South America. It consists of 2 propane flame throwers mounted under each side. If anyone tries to open the locked doors or threatens the driver with a gun, the driver can activate both flame throwers instantly.
The main problem with an electrical discharge security system is that it must be well designed otherwise you stand to fry all your electronics with the EM field.
Or, you can hire a bouncer to stand beside your car! hehehe.