Found this on the Freakonomics blog...
Tagliamonte’s son lost his first tooth when he was nearly seven; the parents didn’t know how much to pay, so they asked their son. “He asked for one penny for his first tooth,” Tagliamonte writes, “but wanted to double it to two cents for the second tooth, which was also loose. … We’re now up to 64 cents for the forthcoming seventh loose tooth with the stipulation that once he receives $10.24 for the 11th tooth, all subsequent payments, including the $5,242.88 payment for No. 20, will go into his 529 college-savings account.”
Damn! How could I miss this opportunity to make thousands of dollars!