I remember there was a thread on here where MTF voted 80-20 that Pete's serve was better than Roddick's and better than any of the current players' serves, bar Karlovic - even though several of today's players register much faster speeds. I don't agree with this (and I'm often called a Fedtard Pete-hater for this reason!) But let's look at the evidence.
I've posted links to Federer-Sampras and Federer-Roddick in Shanghai 06. A lot of people believe that Pete's disguise and placement compensates for the slower pace of his serve compared to today's big servers (Roddick, Ljubicic). I think a comparison between these two videos (or pick any Fed-Roddick video you want, even AO 07) shows that view to be a myth. Federer is able to take a full swing at a lot of Pete's first serves and hits several clean winners on first serve returns. Lleyton Hewitt did the same. Against Roddick, however, Roger simply doesn't have time to attack. He can only float a blocked return back, relying on his superior skill to win the point from there. People often talk of how Federer is able to handle Roddick's serve - but Andy usually gets a defensive, floaty response to his first serves from Roger, it's just that he can't take advantage of it. Watch the videos and see for yourself. Andy's serve has a lot more bite on it than Pete's does and draws weaker responses from Roger, even though Andy is facing a far stronger version of Roger than Pete did. Furthermore, the Andy-Roger match is on a relatively slow surface whereas Pete-Roger is on grass.