Encyclopedia of Life

I encountered this website about two years ago when it was not too well developed: The Encyclopedia of Life.  Since then, a lot of information has been added, and the site just continues to grow and  become more comprehensive. You can search for an organism and find information on its evolutionary history, ecology, general biology, as well as relevant scientific papers.

Here is a link for the Koala Bear (I've no idea why I chose it for an example- it just popped into my head). As you can see, there is an image gallery, and information below the images. To the right, there is a classification index that is really fun to play around with.