Has anyone read this book by Alan Weisman? It examines what would happen to the world's flora and fauna and even human constructs if humans were to disappear tomorrow or gradually die out. A lot of it seems like pseudo-science and a lot is definitely conjecture, but has enough truth and sense to be plausible.

It examines what was here before humans, what possibly happened to other species of life once humans became the dominant organism on the planet, how long the planet would take to recover to its previous state once humans are gone, and how human achievements would fare without us around to maintain them.

Very interesting read.