Originally Posted by ********
Then basically Isner or Raonic. Throw in Gulbis as well, I missed him in my first post but he really goes for big second serves.
Of recently retired players, perhaps Taylor Dent and Joachim Johansson. In this article
Joachim talks about hitting second serves around the 200kmh (124 mph) mark.
I did some more research. Andy Roddick is the man.
His 2nd serve average at Wimbledon 2004: 110 mph. He was serving 112 and 113 in the SF and QF, respectively.
And Johansson hit a 130 mph second serve against Roddick in their 2004 USO match. Both of them had similar averages, but Johansson went for more. Although Roddick hit a 122 mph second serve also.