Replying to I need a "green" business for class

i have a class, e commerce and entrepreneurship,  that for first semester we made our own online green businesses and now for second semester our whole class does one business and we compete at an expo at the end of the year. so, i need some ideas for a business that in some way or another is related to going green. we have to make a web site, marketing plan and everything else that the business would need to actually run. PLEASE GIVE ME IDEAS!!!     It can be a product OR service.


sparknotes- give me an idea for a "green" business. either a product or a service.