Pass the buck
Give your child three pretend $1 bills; keep three for yourself. Pass one back and forth while you sing a song. Whoever's holding the bill when the song ends adds it to her pile. Play four more times, alternating whose bill you start with each time. Then help her count the money in each pile to see who won.
Bury coins in a small baking tin filled with sand, then have your toddler find them with a plastic spoon (or his fingers). Identify every coin he unearths, and have him sort his treasure into piles. (Keep a careful eye out -- coins are a choking hazard for kids under 3.)
Pay to play
Throw some bills in a bag, and have your child draw one out to find out how many times she has to jump: a $1 bill means once; a $5 bill means five times. Make up other challenges, like giving ten kisses or taking 20 big steps.
Who's the winner?
Lay out a penny, a nickel, a dime, and a quarter. Ask your child to find the smallest, the biggest, and the darkest-colored ones. Add another set of coins, and ask him to find the two smallest, biggest, and darkest-colored ones.