This site by AKQA for the launch of Halo 3 is just AMAZING! It’s been created using a diorama (yes they actually hand built the entire set). It’s a completely immersive experience and one that I really, really enjoyed. I spent over an hour cruising through the landscape checking out all the detail.
Be sure to check out the “making of” video while you are there as it’s quiet awesome to see the project come to life.