I tried to wear those heels once, but all I got were funny looks. :)
Something to remember; it only takes about 8 lbs. of pressure to rip an ear off. Grab at the top and pull sharply down.
A sharp blow to the point of the nose with the palm of the hand also works well. There are nerve bundles between the shoulder joint and base of the neck, which if struck firmly will cause temporary paralysis. There are also nerve bundles on the mound of the forearm just below the elbow that if struck firmly will temporarily immobilize the arm. The top of the foot near the leg bone is also a painfull spot. One of the best carry on weapons is a belt with a heavy metal buckle. Always carry a sharp pen and a key ring so that the ring fits into your palm when you make a fist and the longest key sticks out between your index and middle finger. The key is to focus and to size up your potential opponent before you have to act so that you have a plan of attack if the need arises.
For effective self defense and great exercise I highly recommend Aikido. No punches or kicks and it works extremely well and it works just as well for women as well as men. In fact if you attempt to use any strength at all in executing any of the kata is means you're doing it wrong. I have used my Aikido at school more than once successfully. Aikido is, btw, what Steven Seagal uses, at least in his early flicks.