With this one you can, if you don't mind me saying, kill two birds with one stone. You'll be recycling and helping animals at the same time.
Have you noticed the machines at supermarkets and other places that you can put bottles, cans, and other recycables in? Usually you get five cents for each bottle, can, jar, etc. When you raise enough money you can adopt an animal online at www.wwf.org or www.nwf.org or you can give the money to an animal shelter/other environmental organization.