I could not have said it better than what I read below.
Text taken from TrojanWire in its entirety
But it wasn’t the first touchdown that will resonate in the minds’ of those in attendance. It wasn’t Booty or Stafon Johnson or any other Trojan who played at the coliseum that September 1st…but rather who was missing from the roster that will be remembered. Immediately following the touchdown, everything seemed normal. The Trojan extra-point unit ran out, taking the usual formation on the field. But something was missing -or rather somebody.
There was no kicker to be found.
At first, every person in the stands was hollering about such an obvious mistake. Then, one by one, they started to quiet as everybody realized what was taking place. The statement the team was trying to make was slowly sinking in. And in moments the coliseum fell completely silent.
The referees were finally forced to throw their flags, charging the Trojans with delay of game and a 5-yard penalty.
USC kicker Mario Danelo died tragically on January 6th, 2007. The players had asked coach Carroll if it would be okay to leave the first kick for him. It was a kick that everyone felt rightfully belonged to Danelo; a kick, however, that could never be taken. But it was in this simple moment of silence that the USC Trojans found the perfect way for Mario Danelo to enter the coliseum, and take a bow for the Trojans for one final time.
Well done, gentlemen…
Fight On! Mario, you will be missed, R.I.P.