Minute to Win It games. NBC.com used to have a big list of games they used and instructions, but they must have taken it off their site. Search the web for them, though. I've done it twice for family camp with all ages, but was careful to choose ones that aren't way too difficult, and that used things I already had or were cheap.
Some that I've used were:
Penny Hose- put a penny in the foot of each leg of a pair of panty hose. Participants have to retrieve the pennies by sticking an arm in each leg- but one hand can't help the other hand.
Breakfast Scramble- cut the fronts of cereal boxes into 16 rectangles and the players have to reassemble them.
Pencil Flip(?)- don't remember the actual name. Start with one pencil (unsharpened!) balanced on the back of your hand. Toss it up into the air and catch it with your fingers. Keep adding pencils until they fail.
There are tons more if you look- and all have to be done in a minute.