Hope you've been recycling. If not, your news feed, inundated with Earth Day stories, will make you feel bad about yourself and remind you about the greater good.

This year, the angles, which have already begun to circulate, will most likely be Earth Day's 40th anniversary and green apps.

Traditional green branding will continue for the usual suspects like Kiehl's, which asked four celebrities to design labels for a product that benefits the Rainforest Alliance, and, Avatar, which will leverage the release of the DVD on Earth Day.

What do you think is the most innovative Earth Day campaign, past or present?