Um, to my knowledge, Federer is one of the few players around today with good net skills. Ok, he might miss easy volleys now and again, but he is natural up at the net. If you don't come to the net as much as you did/should then you will make mistakes.
He volleys with his 'feet' instead of his 'hands' (a flaw in which is common among horrible net players), his anticpation and his reactions promote his net play combined with a good wing span he could have easily had a great career serve and volleying on the faster surfaces. He did implement this strategy when he was younger, I'll remember the Wimbledon 2003 semi-final with Roddick as one of his greatest s&v performances on a current surface.
The only players with a better net game than Federer are Mahut, Llodra, Lopez. Other players with natural volley techniques and don't look stiff (ala Roddick or Soderling and some cases Nadal on above average volleys) include Djokovic who is just a natural hitter and Murray. Neither of these guys come to the net because A) In Djokovic's case, he doesn't need too and B) Murray doesn't isn't aggressive enough to do. I will revert back to say Nadal does have intelligent approach shots, which makes up for maybe the fact he can't execute tough volleys. Federer sometimes gambles on appraoch shots (similarly to Roddick), but has the reflexes and hand/eye coordination to be effective.
Federer is quite flexible which helps him get to some difficult passes/lobs.
Just my opinion anyway.
