Retirees, here's your new purpose in life

If you're over age 60 and you have a great idea for giving back to the world or just your neighborhood, here's some inspiration -- the $100,000 Purpose Prize. It's awarded annually by San Francisco-based Civic Ventures that honors older people who started a second career that benefits society.

The 2008 winners were just announced, and what a batch. The six $100,000 winners did amazing stuff, from inventing a $28 peanut-shelling machine that helps African farmers be more efficient with their cash crop to teaching life and career skills to prisoners at New York's Rikers Island. (There were also nine $10,000 prize winners who do equally admirable work for their communities.)

The Purpose Prize is especially valuable these days because many foundations, which give prizes like these as grants, are being hit hard by the economy and not as able to give out free money.