Oh, and back to the point: greatest shots....
This one was never on television, but I've got to mention it.
I saw Jose Luis Clerc get back to a lob by Brad Drewett in an early round night match at the Open once. The shot made me want to play every single day. Naturally, his back was to the net and he was running near full speed. He hit it with the forehand side of his stringbed like a 'between-the legger", but the contact point was on the outside (right side) of his right calf. And, man, he spanked this ball...and it went in!
Other great shots that would happen with a little more regularity:
Becker's backhand return of serve. Oof. Inspiring. Saw him practice once and he seemed to have so much control over it, even though he was absolutely bludgeoning the ball.
Sampras, Rafter and Noah on the overhead. Just a little extra-special.
And finally, this one time [at band camp?], when Lendl was clearly trying to hit John McEnroe really hard in the stomach. He took a massive cut at an easy forehand..Mac sort of caught the ball with his strings and somehow delivered an impossible little angled drop volley. I'm sure this happened all the time, and Mac probably got more than his fair share of bruises, but my first time seeing this made me want to be at the net all day.