Shatner should recieve more credit himself, as he performed some great stunts on TOS; someone already mentioned the fall in "Journey to Babel," but another notable stunt was the close up of his leap/kick over the med table in "Mirror, Mirror" and the fights with Tracey (both) and Cloud William in "The Omega Glory."
It really paid off when Shatner was cleary involved.
That's right. I would add the flying drop kicks he delivered in The Paradise Syndrome and Spectre of the Gun. If I'm not mistaken, he was taking karate lessons on his own time.