Here are some more additions to The Best Sites To Learn About The Gulf Oil Spill:
Spill Effects Underwater is a NY Times graphic.
U.S. Oil Spill explained is an excellent animation from Al Jazeera English. Unfortunately, though, it’s hosted on YouTube, so may not be accessible to schools.
Animation of Oil-Spill Cleanup Methods is a video from The Wall Street Journal.
The Chicago Tribune has a ton of resources on the spill, including many graphics (scroll down to the bottom of the page).