Have not looked into buying one or the legality of it, but it could be worth carrying. It may bring back visions of old cartoons.

http://blog.wired.com/gadgets/2008/07/unbreakable-fig.html

i once saw a website with a bulletproof umbrella... I think the site is down though

Here is the company's website (usual disclaimers, no assoication, etc, etc):
http://www.real-self-defense.com/umbrella1.html

Unbreakable is one thing but if it won't pop inside out in a strong wind, that's way more valuable!

I have never used an umbrella in my life, but I like it!!!

Sounds like a device for the a post-apocalyptic Mary Poppins.

With one hand she rides her bulletproof umbrella across the sky. Hosing down unbelievers with a H&K MP5 with the other. She rides at the front of her evil army of dancing penguins, bluebirds and chimney sweeps.

The horror.
The horror...