Ever wondered what Manhattan had been like back in 1609? No? Well now you don't have to wonder; The Wildlife Conservation Society in conjunction with Pond Media & Design has put together a Google Maps mash-up of sorts called The Mannahatta Project that shows a satellite view of what the city looked like when it was teaming with wildlife rather than people. When it was a real jungle, rather than a concrete jungle. When it was a... okay, I'll stop there. You get the idea.
The map is so detailed you can go block by block and get a report of what wild life used to live there, and what's there now. Pretty amazingly detailed stuff.