I *almost* got tagged by a copperhead, too.
I was hiking through the woods heading to a backcountry cliff for a day of First Ascents(rock climbing), and as I stepped with my right foot up onto a small embankment, a copperhead shot out towards my left shin, but wasn't quite big enough to reach me with his strike.
I also pulled up onto the top of a boulder once here in the desert, and as my eyes came up over the top, I was greeted by beady eyes, and a violent rattle. I couldn't tell you what kind of rattlesnake it was or even if he actually took a strike at me. I let go of the rock and took the 15' fall with no reservations about it. I did NOT want a bite on my face from that guy, MUCH more than I didn't want to fall 15'...