We can't undo the damage, but we can take steps to fix the problem. The National Parks Foundation is taking text donations. Just text "parks" to 90999 before July 1st to donate $10. If you live in the area, Deepwater Horizon Response is looking for volunteers, as is the National Wildlife Federation. These jobs range from clerical work to trying to spot endangered species and new oil slicks. Also, don't boycott Gulf seafood: it's been certified safe by the National Fisheries Institute and it supports many of the small businesspeople.
Part of spill is everyone's fault, because we all use petroleum. We all drive cars, we all use plastics. We can decrease our use, but that's going to be tough. While we can clean up after the disaster, the best way to prevent more disasters is to reduce our oil consumption.
It will probably take longer - my 45min drive to school takes about twice that. But take this into account - what can you do when driving? Nothing but drive and maybe listen to music. When I take the bus, I get to spend the time studying, reading, or sleeping if it's getting close to midterms. I consider this less wasted time. Just be sure you leave with extra time to spare in case the bus runs late.
I know it's not feasible to give up your car right now. I even drive to my bus stop because I live far from the stop. We're a more suburban culture than in mass-transit-centric Europe, where the habitation areas are more nucleated. But save the car for groceries, hauling big stuff, and going to unusual places. Carpool when possible, and combine little trips into one large trip to save on emissions.
Give it a shot! Let me know how it works out. Have you had good experiences? Poor ones? Why?