Gack. There oughta be a law.
So where can one go for the straight truth?
Well, I was impressed by factcheck.org's review of the birther conspiracies, "Born in the USA."
Here, for example, is a hi-res photo of the birth certificate showing the raised seal. And the article lays out the arguments, and debunks them effectively.
It won't change a true believer's mind, but it's an impressive piece of research work! You go guys!