In the past there have been a number of customs involving shoes which were thought to bring good luck. The best known, which is still upheld, is to tie shoes to the back of the newlyweds' car. This has evolved from the Tudor custom where guests would throw shoes at the newlywed couple. It was considered lucky if they or their carriage were hit. (I wouldn't call it lucky if I was hit would you.)
Less well known is for the bride's father to give the groom a pair of the bride's shoes to symbolise the passing of responsibility for the daughter to her new husband. A variation of the custom is for the groom to tap the bride on the forehead with one of the shoes to assert his dominance. (oh really!!!!).
The custom of the bride throwing her bouquet over her shoulder, was originally performed by her throwing one of her shoes over her shoulder.