The Consumerist has posted a giant round-up of their advocacy articles called "The Ultimate Consumerist Guide To Fighting Back." It breaks down into three sections:
Section 1: "I've been wronged! What do I do next?"
Section 2: The Consumerist Corporate Executive Directory
Section 3: Success Stories
and each section contains links to excellent articles on everything from timestamping your communications with customer-service lines to "launching an executive email carpet-bomb" to the delightfully named "Underlying Principle For Forcing An Uncaring And Adversarial Company Fix Your Problem." The next time I'm ripped off, I'm starting here. Link