Magic Fishpond (Ages 3 to 8)
Hang a sheet across a doorway, high enough so children can't see over it. Give children a "fishing pole" with a small basket tied to the line, and have them drop it over the sheet. The Magic Fish (you or a helper) on the other side tugs the line, and the child pulls out the basket with a prize in it. Let guests "fish" several times.
Musical Hoops (Ages 3 to 6)
A noncompetitive twist on musical chairs: Start with each child standing in a plastic hoop on the floor. Play music as children dance around; take one hoop away. When the music stops, two children share a hoop. As the game goes on, more and more kids squeeze into fewer and fewer hoops. At the end, all players must fit in one hoop, helping each other stay in.
Dress-Up Relay (Ages 4 and up)
Set out two baskets of dress-up clothes. Divide kids into teams. On "Go," the first child on each team runs to the basket, puts on two items, and runs back to tag the next player for his turn. Everyone gets prizes. Alternate: Put the dress-up clothes in one pile, and give kids five minutes to make their own costumes. Give prizes for the wackiest, most elegant, most colorful, etc.
Treasure Hunt (Ages 6 and up)
Hide innocuous items around the house or yard; it doesn't matter what you hide. Divide guests into teams and hand out clues written in silly rhymes; encourage the kids to solve them together. Set a time limit (30 minutes). Give prizes to all.
Fortune-Telling (Ages 8 to 13)
Set up a tent of sheets and have a fortune-teller (you or another adult, say) dress the part. Make fortunes positive or even goofy. Have activities for other guests to do while kids are in the tent hearing their fortunes.