It's easy to get turned off by protests, to say that direct action, sit-ins, arrests are counterprodcutive and don't make any difference. But then you read something like this and you realize that, over time, in-your-face activism can have a very direct impact.
Paul Watson founded the Sea Shepherd Society in 1978, after he left Greenpeace (which he also help found) in a battle over tactics. Greenpeace was always scrupulously nonviolent; Watson wanted to take things a step further. He bought a boat and started hunting down whaling ships; his first victim was a pirate whaler called the Sierra. He rammed his boat repeatedly into the Sierra's hull off the coast of Portugal in 1979, nearly sinking it. An anonymous bomber finished the job a year later, blowing a huge hole in the whaler's hull while it was in port.
Since then, Watson and his crews have made life miserable for whaling ships (check out this picture of a Sea Shepherd crewmember tossing a bottle of butyric acid -- which is harmless but stinks really, really bad and would make conditions on the boat almost intolerable).
And it's working: It took years, but Japan is now pulling back its whaling fleet, blaming the Sea Shepherds in part for making whale hunting too costly.