Media Matters has a list of right-wingnuts whose speech is far worse than Imus. It has links to audio or video of some of the examples of these douche-nuts' bigotry/racism/xenophobia/sexism.
I don't think Imus should have been fired, due to free speech. Perhaps many people could've boycotted Imus, which might have caused his ratings to drop so much that he would get fired for low ratings. I think that would have been more effective in opposing bigotry than firing Imus. However, if Imus was not fired, he might have cleaned up his show. Supposedly Imus did not have a history of extreme bigotry like mAnn Coulter or Michael Savage.
If anyone should be fired due to bigotry, it's Coulter & Savage.