Two memories that come to mind:
Watching a mink chase a rabbit under my treestand. It was like a beagle/rabbit chase, but in slow motion. Over the course of about an hour, the rabbit passed my stand three times, with the mink trailing far behind, but on the exact path the rabbit had passed.
Another cool thing was watching a woodpecker pecking around the top of a tall, dead tree trunk, and chase a flying squirrel out of a hole. They went round and round the trunk, with the woodpecker pecking at the flying squirrel. Finally, the squirrel leaped off the tree, and glided down past me, just a few yards away, and when it was about five feet from the ground, using its tail like a rudder, made a ninety degree turn, and landed on the trunk of another tree about forty yards from where it started.