Ridiculous though it may seem, Stephen Colbert is testifying before congress this Fridayabout immigration reform . While not an expert on the subject, he did devote a day to working on a corn farm in an effort to raise awareness about United Farm Workers and undocumented immigrants. But it's not his expertise the savvy politicians behind his testimony are after, it's his celebrity.
It's not hard to understand the appeal: Celebrities, by virtue of being famous, are able to bring considerable attention to the causes they choose to represent, which is why they're often asked to come before congress and spread their tail feathers. Here are six examples of famous folks who went to Washington for a cause.