In this months Fitness magazine, there is an article about finding the right shoe whether you are a walker or a runner. First you find out what your foot type is. They have you wet your foot and then step on a paper bag to see what the shape is (flat arch, normal arch or high arch) and then there are shoes listed based on each shape. Apparantly the people at Fitness tried out a TON of different shoes to come up with the winners and runner-ups for running and walking shoes.
I need to buy some new shoes myself and found this very helpful because I never know what to look for.