I really envy some players like Federer who can catch the ball from the ballboy with the side of his racket, Marcos Baghdatis bouncing the balls between his legs before a serve, and even Roddick walking the ball over to the service line.
I remember Agassi catching a fairly fast return of serve (from a serve that was called out) right on his strings, but perfectly timed so it looked like there was velcro on the strings and the ball just stuck to it.
Last of the moon-and-volley specialists.
I believe in luck. How else can you explain the success of those you don't like? ---Jean Cocteau
Santoro is another guy for tricks (and just general random stuff during matches). And I definitely remember seeing Coria balancing the ball on the side of his racquet.
I believe Baghdatis picked up the trick of bouncing the ball between his legs from Federer - I can't remember the quote exactly, but he saw Federer do it once in a match and just started doing it all the time. I know I've seen Feds do it a couple of times too.
Mansour Bahrami was the King of tricks. He would flip and twirl his racquet around, hit shots between his legs or behind his back, spin the ball so it would bounce back to his side of the net, would bounce a ball high into the air and catch it the pocket of his shorts, serve holding 5 balls in his hand, he was fun to watch.