Bubbles and different sized wands.
My 4-year-old daughter made up this game, and I thought it was rather clever! As I blow bubbles, she pops them with her finger and says a number, starting with the number 1. As the bubbles float by, she pops them and counts the next number, and the next, until she forgets what number she was on or can't count any higher. Because the bubbles come out at different rates, the game requires a one-to-one correspondence understanding which is essential to the concept of what numbers represent. It reinforces sequencing and is fun and motivating. It is also great for those kinesthetic learners out there! You could also do it with the alphabet, or with more open-ended groups such as colors or animals. Happy popping!