Scruge - Thanks for the template! No Google query I've tried gave such a concise answer to my question. With this I was able to make a rough parabolic LLPR from foamboard and aluminum tape held together with hot glue. At the focal point, I use a stock USB adapter.
http://img74.imageshack.us/img74/5882/test13cx.jpg
The initial results were very good - better then any of the other homemade antennas I have yet tried.
I intend to make a larger, more precise version. My question is this: Assuming that I want to make a connection with a distant AP, and not passively listen, would making a deep reflector with a focal point far inside the "dish" direct more energy to the AP then a shallow dish with the focal point outside the depth? I assume that the dipole I intend to use radiates evenly in 360 degrees from the polarity, and having it inside would reflect more in the direction I want, but I havn't seen any designs to this effect anywhere.