A Whole Blog on Deniers!
Via Pharyngula, there's a whole blog just dedicated to dealing with the various deniers (holocaust, AIDS-HIV, creationists) that I have a discussed in other posts. They do a better job of defining denialism much better than I have: "The practice of creating the illusion of debate when there is none."
They also define deniers better than I did, by defining them by the tactics they use.
Check it out.