A nifty calculator to satisfy all your curiosities about the human population. You could even play a rousing game of Where's Waldo? while on the site. (You won't find him; although we did see his blue-stripe-shirted cousin.)
A list of pretty much every big ecology resource out there on the interwebs. It's ginormous.
Find out what ecologists do in their free time (hint: they visit this website).
The Earth on Edge, from PBS. They have tons of info on the different ecosystems, plus an interactive quiz (since we know how much you love those).
Documentary clips from Planet Earth. You have no idea how much we love this show. We've almost worn out our copy on DVD.