Relay races, three-legged races and other fast-paced competitions are a great way to get rid of your young guests' excited energy before they sit down for some cake and ice cream. Depending on the ages of the invitees, you can either pair up people you think would work well together or allow them to choose their own partners. For the younger set, these are also good parent-child activities.
Try to incorporate your party theme into the races. For instance, if you're going for wacky, how about a dress-up relay race? Participants have to put on an item of funny clothing or an accessory each time they run to their partners. The first pair wearing completed outfits wins.
Obstacle courses are also crowd-pleasers, although they may require more preparation on your end. Like relay races, you can design an obstacle course to suit the occasion. For tween girls, you could set up a glamour course with makeup, costume jewelry and hair accessories. The girls have to dash through, apply their makeup, fix their hair and toss on some baubles as fast as they can -- without looking like they sprinted through a wind tunnel.