How about combining snack time and activity time during a party? Kids love doing arts and crafts, and kids love to snack. It's a win-win.
Give each child a white plastic or paper plate (i.e., the "canvas"). Tell them they're going to create works of art, and then they're going to eat them. Provide them with ample "art supplies," like celery and carrot sticks, cucumber rounds, slices of fruit, and lettuce leaves. Don't forget "decorations" like seeds, nuts (only if nobody at the party is allergic!), raisins, olives and beans. Then give your budding artists some "glue." Think peanut butter, ranch dressing, cream cheese or cheese spread, and yogurt.
Encourage the kids to create something special -- a car, dinosaur, flower or anything they can think of. You can even take souvenir photos of the kids with their creations before the kids devour them.