These earrings, made from recycled bottle caps, are cute and give you a chance to tell others about the cause. Says the artist:

My designs hope to spread positive messages not only in the image design, but with the interaction you will have with others when you wear them. More importantly, they are a small donation to Mother Earth by helping conserve her resources.

You can find tons of designs on her website, and the prices are extremely affordable. On top of being recycled, she donates part of her profits to The Adelante Foundation, which helps women living in poverty.