The World Wildlife Fund offers an adopt an animal program.
For a gift of only $25, WWF will send you a photo of your chosen species and an adoption certificate as a keepsake. For $50 or more, you get a stuffed animal too. There are 40 animals to choose from - anything from a snow leopard to a clown fish.
It's a great way to teach young kids about protecting nature and it gives them a sense of a responsibility. You can get started here.