The Nature Conservancy, The New England Aquarium, Lauren Conrad, and Jess Rizzuti . But if you need a more comprehensive guide, take a look at TreeHugger's 2012 Gift Guide. TreeHugger composes the best gift guides on the web, so you're sure to find something for everyone on your list!
Some of my favs that I found through TreeHugger are:
Agate Plates & Coasters from VivaTerra
Earrings from Lulu Frost
Upcycled Clutch Made from Books from Conduit Press