J.A.
We did a scavenger hunt for our kid's 16th birthday parties. We assigned each group of kids an adult driver - didn't want teens to be "racing" around town - and gave each team a list of items with a point value attached to each item. They had one hour to get as many of the items on the list as possible.
The list included some video items so we borrowed video cameras from friends for each team. When all the teams arrive back, you add up the points and watch each teams videos. It's a lot of fun and very inexpensive.
You can serve food and drinks during the video portion of the party. Prizes can be as simple or elaborate as you want them to be.