It's often hard to get an airline to acknowledge that it's screwed up, but musician Dave Carroll came up with a pretty effective way to respond after United Airlines broke one of his cherished guitars: writing a series of songs about the incident and putting them up on YouTube.
Carroll tells the full story on his site, but the brief version is that after a year of fruitlessly pursuing his claim, he decided to instead write a series of songs about the experience and make them available via YouTube. That seems to have finally elicited a response: according to the United Airlines Twitter feed, the airline is now looking to compensate him, though at this writing there's no confirmation of that on Carroll's own site.
As the Roaming Tales travel blog (where I first encountered Carroll's story) points out, this is the social media equivalent of a common phenomenon: consumers finding their problems solved rather quickly once they complain to a newspaper or magazine columnist and the threat of widespread publicity looms. The novelty of Carroll's approach probably helps, but there's no doubt that airing your (genuine) grievances on Twitter or in other media can help get them resolved.