Too many to list 'em all, but my most recent banning:
You see this place? I joined because, although a Liberal (moderate), I am also a survivalist nut and a huge fan of the SKS. I did not like the floating firing pin, and through these boards I was able to purchase and install a spring-loaded firing pin that works much, much better for my peace of mind. So I joined.
What they don't show mere pedestrians is that there are subforums of that board only members can see. Teabagger subforums. Lots of them. The owner of the board is a rabid teabagger, a birther, and a racist who perpetually laments the "war" that Mexico is "waging" on us. (He's also a born and raised Houstonian, and insists that any Texan living north of Houston is a Yankee.

) Needless to say, but I will anyway, the majority of the members on that site are, in fact, also teabaggers.
So when an atheist with a past in bible study, raised on welfare, middle class, liberal, mixed race member joined, it quickly got ugly. My favorite was when one of the long time members, an old white man from Arizona (coincidence?), threw a complete tantrum over all the brown people "with no religion" invading his country, and told me that if I didn't love Jesus, I needed to "get out of this nation."
I responded with a profane series of graphics where Elmo the Muppet taught him the constitution, and was subsequently banned.
Amusingly, I searched my username over there just now, and they are paranoid that any new member who joins that shows even slightly Liberal tendencies is now me under a sock puppet account. (I have not done this.) I was banned months ago. Bitchez know my name, verily.