ESPN attempted to compile the greatest individual single-season effort for every FBS football program, and while I haven't been through the whole thing, I think they at least got it right with NC State. Their pick was Philip Rivers' 2003 season, which is tough to argue considering not only the gaudy raw numbers but his efficiency as well.
They also listed some honorable mentions (Torry Holt 1998, Ted Brown 1978, Mario Williams 2005), which left me trying to figure what seasons--if there are any--that might reasonably compare to Rivers' senior campaign. Holt's last year in Raleigh is pretty close, but it's hard to get beyond the fact that the quarterback influences so much in any given game.
Brown's 1,000-yard seasons don't really feel impressive to me, and it hasn't been lost on me that this impression has been affected significantly by everything that's happened in college football since then. Barry Sanders, Ron Dayne, LaDainian Tomlinson, Ricky Williams--it's all their damned fault. Brown might have a legitimate case, it's just difficult to put his numbers in their proper context after all this time.
Is there an argument for David Amerson's record-setting interception spree in 2011? Averaging an interception per game is pretty nuts, but would you consider that enough to vault him ahead of what Rivers or Brown or Holt or Roman Gabriel did in their time?
I'm probably missing a few other candidates here. Anybody else that you'd throw out for consideration?