The First National Bank of Dad: The Best Way to Teach Kids About Money by David Owen
Kids experience time more slowly than adults do. A year is a lifetime to a kid, so David Owen proposes giving a young kid interest earnings in terms they can get excited about. I'm giving my 9 year old son 5% interest per month and though he spends occasionally, he is very committed to saving and to earning more to put into his account so that it can grow.
The idea of giving your kids monthly interest to incent them to save is terrific.