Microsoft has created Terrarium, a multiplayer ecosystem game developed using the .NET Framework. Developers can create their own creatures and add them into the game on their own client machine. Teleporters on each client transfer the creatures between clients in the Terrarium peer-to-peer network. As a creature developer one can program either herbivores or carnivores. Terrarium makes use of XML Web services and peer-to-peer networking. It looks like an interesting way to learn more about the .NET Framework. Oh, you can also win an Xbox.