Retirement can sometimes be the time to start really making a contribution.  When John Mika, 58, discovered how much teachers in Buffalo, N.Y., were spending, out of their own pockets, for school supplies, he decided to do something about it:

Name: John Mika

Role: Substitute teacher, everyday philanthropist

The Problem: As a substitute, he discovered many teachers were spending as much as $500 a year, out of their income, to provide pencils and other supplies.

The Innovation: He opened The Teacher’s Desk, a donated warehouse that stocks an inventory of donated school supplies. Teachers shop there for free.

The Benefit: Since October, 2011, Mika has supplied 1,247 teachers with materials worth $374,000.

—People magazine