Great thread!
DD keeps a container of kiddie trail mix, with Fruit Loops, raisins and tiny goldfish crackers in it for the twins. I keep Rumbly Grahams on hand for them at my house. They also like fruit chunks - right now it is cantaloupe and watermelon since we are surrounded by them. And as the grandma, I have to admit I have Ice cream cones for them at all times.
How about some yogurt with stuff in it? Good for calcium. Or ham and cheese rolled up and cut into bite size rounds? That would be good for protein.
I'm sure the others will have some good ideas...
Jana