All Hall of Famers except Manning, who's a lock for future induction, and Ken Anderson, a guy who in my opinion is worthy of enshrinement (maybe I'll write about that in the future). If we expand the list to include the guys who've won 2 passing titles we add:
Graham and Unitas---legends. Thompson was a great QB back in the 1940's who won two championships with the Eagles and he might well be an overlooked HOF candidate himself (more on that soon). And former bagboy Warner was great for three years before flaming out spectacularly for still-inexplicable reasons. So out of the 11 men who've led the league in passer rating multiple times, seven are in the Hall, one will be, and two more are decent candidates in my opinion. Only Warner is totally out place on the list. It sure looks like winning two or more passing titles is a sign of passing greatness.
What active players have a shot at joining this elite group in 2007? I'd say none. Besides Manning, the only active passers who've already led the league once in passer rating are Warner, Steve McNair, and Chad Pennington. Warner's finished, McNair's hit the wall, and Pennington's passing crown was 5 years ago now and he's been in decline ever since thanks to injuries and age.