Logical fallacies - I did start a collection of my own to put up on the main site. I wonder where I have them stored?
I think understanding logical fallacies is a must for skeptics. It's not until you get a grip of things like post-hoc reasoning, arguments to authority, arguments to ignorance etc. that we can see where people's reasoning goes wrong.
Once you've studied logical fallacies, watching Question Time is never the same either.