In Downieville this past summer, on my second run of the day down the XC course, just past the third bridge and most of the way up the last real climb of the run, I saw a bear on the side of the trail.
For a moment it seemed nearly as startled by me as I was by it. Then, looking over its shoulder at me, I swear it practically shrugged. "Oh, another of you damn bikers."
I looked around for cubs, and thankfully found none, so I stood there watching it, a black bear standing perhaps four feet at the shoulder, as it wandered down off the hillside, onto the trail, and ever-so-nonchalantly made its way up the trail.
By this point, two minutes into this encounter, I was thinking, "Okay, cool, a bear. Now, I'm riding here, buddy, so can we get this show on the road?"
Finally, he/she wandered off-trail downhill to investigate a berry bush, and I clipped in and spun past as fast as I could, about fifteen feet uphill from it, confident but less than totally sure that it wasn't interested in eating me.
Definitely the coolest wildlife siting of my rides.