One moment stands out clearly in my mind. Back in the early days of the Bush administration, Mickey Kaus had a typically contrarian post in which he suggested that with the rising tide of animosity on the left toward President Bush it was only a matter of time before we saw the outcropping of political violence on the left, to parallel what we'd seen from the right with the Clinton-hatred of the mid-1990s. (Perhaps someone can dig up the post? Late Update: Found.) It was a typically Kausian post, not only for its strained contrarianism but more for its complete failure of predictive value.
Here is documentary footage of my reaction:
(Thanks to Brendan.)