In the future, and given the state of how technology is developing, I see the use of personal "drones" as a means of complex self defense, let me elaborate:

As electro-mechanical technology continues to minaturize, while the complexity continues to increase, building semi-autonomous platforms that provide enhanced surveillance measures and some means of deterrence along with a little AI will provide individuals with advanced warning of a potential threat, as well as an indirect means of neutralizing an attack. Imagine one of these new RC helicopters, like the ones you see flitting around in the malls these days, only equipped with a sub mini video transmitter bluetoothed to your pda. Imagine what could be put on such a platform that would help in keeping you safe and dealing with potential BGs.

Based on what I saw in Iraq, a lot of the tech is already available, and it's just waiting for someone to put it together in a non-lethal package and market it to individuals with a need, or a perceived need, for such a thing.

When it comes to public confrontations, I think it would be a great advantage for any would be assailant to wonder where the counterattack will come from, and in what form. If he's focused on me and takes a pepper spray hit from above from the drone, then that can give me a huge advantage in either escaping the confrontation, or engaging the assailant more on my terms.

Of course, once this tech gets deployed, it will be a short time until BGs figure out how to use it as aggressors.

Then it will really be a matter of who has the best toys, as the Joker would say.