Tom Landry: During his run he won 2 Super Bowl titles (1972,78), 5 NFC titles, 13 Divisional titles; and compiled a 270-178-6 record, the 3rd most wins of all time for an NFL coach. His 5 Super bowl apperances ties Shula for the most. He invented the 4-3 defense and the "flex" defense and perhaps biggest contribution the use of "pre-shifting" where the offense would shift from one formation to the other before the snap of the ball he was also one of the first coaches to extensively use the "man in motion"
At one time FIVE of his former assistant coaches were working as head coaches. Including Ditka and Dan Reeves who have 5 Super Bowl appearences between them.
John Madden: Madden guided the Raiders to 103 victories, 32 losses and 7 ties, including seven division titles and six seasons of 10 wins or more. Madden has the highest regular season winning percentage (.759) for a coach in NFL history with over 100 career wins. In addition, his overall winning percentage (including playoff games) ranked second behind only legendary Green Bay Packers coach Vince Lombardi.
Lombardi: see above and his 105-35-6 record as a head coach, never suffering a losing season
Note: Bill Parcells is not in the Hall of Fame because he has yet to retire, a coach must retire before going into the hall. Therefore, Joe Gibbs is the ONLY Hall of Famer coaching football today, perhaps ever.