Hmm, my current favourite is the Monterey Bay aquarium website. I have a thing for sharks
Not only do they currently have the only Great White in captivity but they have a webcam so you can watch it. The website in general is great with lots of info, and other webcams as well.
The website is at:-
Monterey Bay Aquarium
The Great White is in the Outer Bay exhibition.
StubbyUK