Khan Academy has a great course on critical thinking, which is part of a larger subject on philosophy. I've already discovered my flaws with bad arguments by just watching the first video. Even if you know how to use critical thinking, it couldn't hurt to have a refresher now and then and Khan Academy provides that.
Critical Thinking Course (49 pages of mostly videos with tests scattered here and there)
https://www.khanacademy.org/partner-content/wi-phi/wiphi-critical-thinking?ref=resume_learning#wiphi-fundamentals (https://www.khanacademy.org/partner-content/wi-phi/wiphi-critical-thinking?ref=resume_learning#wiphi-fundamentals)
The whole Philosophy Program
https://www.khanacademy.org/partner-content/wi-phi (https://www.khanacademy.org/partner-content/wi-phi)
I thought this would be good for us in the sense it at least shows us how to spot a bad argument.
I have been a Khan Academy booster since near the beginning. It is a marvelous resource with substantial value because it has such a variety of useful subject matter.
The referenced course would give some serious headaches to our fundie friends.
Oh yeah it gave me a nice head pain just doing the first few practices, and I've been taught this stuff in school.
Cool stuff Apathy. 8)