Well, there is a small minority of "evangelical" atheists who embarrass the rest with vocal intolerance of any sign of religious beliefs, no matter how traditional and watered down. At Christmas they probably go down to the mall and tell three-year olds that Santa is a fraud.
You could argue that they're not so much atheists as religious fundamentalists whose adopted religion is a belief in No-God, the next logical step after moving from polytheism to monotheism, and more strident against monotheists than monotheists were against polytheists. Fortunately they're a small minority.
The most amusing thing I've run across are strident agnostics who were trying to codify agnostic beliefs. I guess they were worried about having the wrong doubts.