For my 12th  birthday party, i had a video camera scavenger hunt.  my parents went to the park and made a list of things, such as find an umbrella, or do a dance while singing row row row your boat while standing on the bandstand. Each team of girls had one video camera, and recorded whatever they needed to find. The items must be done in order, and the last item is to find the birthday cake. the first team to get there got the first slices of cake.