Marble painting. Teaches/reinforces hand-eye coordination, balance, multi-tasking, creativity, and it's just fun. Cling wrap on the top of the box is good for kids who may have difficulties keeping the marbles from falling out (since you can see thru the wrap to the art still). Simple clean up too!
19 Engaging Activities for 1 Year Olds
A great website- all kinds of activities up through middle school age