I can see from my facebook newsfeed that a lot of my USian friends are boycotting BP. BP ignored a lot of safety stuff, had a history of infractions and there's been a huge disaster as a result. This kind of reminds me of the previous, then-largest spill in US history, when the Exxon Valdez crashed in Alaska. They also failed to follow safety regulations or best practices. Their filed statement about what to do in case of spill was similarly bogus (it assumed that all spills would take place in perfect weather on the summer solstice). Angry consumers also wanted to launch a boycott.
It turns out that it's really hard to boycott oil from any particular refinery or source. Oil is fungible and the gas station closest to your house might have a particular brand on it, but they're probably selling oil from many different refineries, including competitors. If nobody wants to buy BP gas at the BP station, the price of that gas will fall and Shell will buy it and start selling it from their own stations. You can hurt BP's retail brand, but you can't touch their refineries and wells unless you cut your overall gas consumption.
I'm not going to talk about car travel, because that's too obvious. But we heat our houses with natural gas or diesel fuel, which is also a petroleum product. We heat our water with natural gas. Taking shorter or cooler showers is a way to stop throwing so much money at BP.
Also, we can be secondary consumers of petroleum. If I buy produce that's flown on an airplane, I'm paying for the jet fuel that brought it to me. So to keep money form BP, I could try to buy more locally grown produce. I could try to get local stuff in general, or just buy less stuff, and thus give less money to BP.
Plastic is a petroleum product. Reusable shopping bags and reusable water bottles will keep money from BP.
A lot of electricity is generated from natural gas (including some which comes from plants that are supposed to be solar. They make up for cloudy days with gas), so turning stuff of at night, etc keep money from BP.
Now, obviously, because oil is fungible, these same steps keep money from other oil companies too. But, really, every oil company is up to no good someplace in the world. Shell is not currently causing problems in the US, but they're doing all kind of bad things in Africa. Exxon (now branded Valero) hasn't spilled anything in the US recently, but the Alaskan coast still hasn't recovered - and neither have the workers who tried to clean up the spill without being provided proper safety equipment. Basically, there's no such thing as a good oil company. And BP is the one that's currently causing problems in the US, but every oil company is causing problems for somebody somewhere. Oil is dirty and toxic and often under places of great natural beauty or places where people inconveniently live (but can be removed from with armed violence). Countries that we might not want to be best buddies with sell us a lot of oil. And burning it causes stronger hurricanes and will eventually melt the world's coral reefs.
So boycotting BP is a good start, but if we want to get serious about this and ensure real change that prevents stuff like this from happening in the future, we need to think bigger. Many countries require relief wells to be drilled at the same time as regular wells. Congress could pass a law requiring that if we ask them to. They could legislate that best practices be followed. And the US uses more petroleum per person than any other country - totalling a quarter of the world's oil. That makes us vulnerable to spills and foreign powers. BP is just a tiny piece of a much larger problem that spans an entire industry and the way our lives are organised. If we want to fight them, we need to stop requiring so much of what they sell.