I mostly like laughing at the loons.
Every once in a while, someone will present an argument that forces me to think. Usually it is because the argument is so terribly bad that I have to take a lot of time to dissect it to understand why it is so bad.
Occassionally someone will present an argument that is pretty good, and I am forced to do a little research and logical thinking to try to refute it.
Also, sometimes someone posts something with which I agree, but in a better way than I could have put it, or from a view point that I had not thought of before.
So, I guess the intellectual stimulation (quit laughing, guys!) is the main reason I post here.
I will also say that when I was feeling out of place when I was in graduate school, this message board (and a couple of others) kept me feeling somewhat connected to something more than my text books.