Media Matters is doing the right job. Check out a post from today about O'Reilly. They have a quote from O'Reilly saying "[i]f you attack someone publicly ... you have an obligation to face the person you are smearing. If you don't, you are a coward."
O'Reilly called Media Matters "paid assassins" who will _never_ appear on Fox News Channel. In other words, O'Reilly Calls Himself A Coward, because he is not fulfilling his obligation to face the people he is smearing.