Steve Young has the highest passer rating for a career, and most consecutive seasons leading the league in passing (4). He is also tied for the most seasons having lead the league in passing with 6, tied with Sammy Baugh.
Len Dawson lead the league in completion percentage 8 times.
Chad Pennington is 1st in career completion %, followed by Kurt Warner & Steve Young.
Johnny Unitas is the only player to lead the league in TD passes 4 years in a row. Also NFL record 47 straight games with a TD pass.
Bernie Kosar once attempted 308 passes before being intercepted (NFL record).
George Blanda threw 42 INTs in 1962.
Neil O'Donnell has the lowest interception % in NFL history.
Vinny Testeverde has more passing yards than Manning, Montana, Unitas, Young & Aikman.
Just fun facts.

*Disclaimer: I think most of the stuff I found was only up to 2008 so some of these records may have changed.