Amazing race birthday party for teenager?!
Games: You could have a scavenger hunt in your neighborhood, do classic games in your backyard (like potato sack races, eggs on a spoon, etc.), and have clues to the next challenges. You could also have fun ones like slip n slide racing, kareoke, etc.
Cake: you could ask a bakery to do a game board and write 'Amazing Race' on it.
Prizes: lotions & body sprays from Bath & Body Works if it's girls.
Hope this helps(:
Treasure or scavenger hunts are the way to go and some quality old style games like Twister and dunking apples! Ebay always have things on that are slightly different including personalised things and ready made treasure hunts.
Wii fun nights are also always a good idea and you can have tournaments!
Random Bocce ball is always fun.
make sure you have a challenge where you have to eat some gross cultural food. Sweetbreads or anything like that