"If they achieved that goal, the co-founders promised to sumo wrestle on the front lawn," Page says.

Yahoo's newly formed green team banded together to offer information and education leading up to the event, and reminded people throughout the week to carpool, turn off lights and shut down computers at the end of the day.

"It was an easy, fun, creative way for people to get involved," says Page, who was hired on Earth Day of 2007 and watched the founders in full sumo suits wrestle on the campus lawn. "That made a lasting impression on me."

Since then, Yahoo's green team, with now more than 300 volunteer members, has launched dozen of creative green initiatives, including a "chuck the cup" program where volunteers handed out mugs to employees to reduce disposable cup use. "On a typical day at the Yahoo campus people threw away 4,000 cups a day," Page notes.

To illustrate this, one Yahoo employee built a series of sculptures that were each made out of 124 discarded cups she'd retrieved from garbage cans and glued together. The resulting exhibit was displayed in front of the main building like a series of giant space mushrooms.

"Each dome represents how many cups are thrown away every 15 minutes on the Yahoo campus," Page says, noting that the statues garnered such an positive response, the green team has reused them several times at locations around the campus. "It's like a guerilla art installment that lets people visualize their waste."

Don't Forget Your Customers

Encouraging and rewarding customers for participating in environmental programs, such as paperless billing or using cloth bags over plastic, can help companies reduce their environmental impacts and foster loyalty among environmentally savvy consumers.

An innovative example of this strategy was recently implemented by London-based retailer Marks & Spencer, which launched a partnership last month with Scottish and Southern Energy. Called M&S Energy to encourage customers to reduce their energy usage, the program rewards customers who sign up to receive advice on ways to reduce energy use. Those who reduce their annual energy usage by 10 percent in the first year will receive a £15 (US$15) M&S voucher. Customers also receive vouchers for both signing up and opting for paperless billing.

"The energy sector can be quite complex and we want to make it simpler for our customers," says Carl Leaver, director of international, home and M&S Direct. "We also understand that the cost of living has risen for many customers and we hope to encourage them to save money by reducing their energy usage, as well as giving M&S store vouchers as rewards for doing so."

Sarah Fister Gale is a Chicago-based freelance writer.