Showtime has debuted a 5 part documentary series called "Full Color Football: The History of the American Football League."
It's a little bit slow moving, but some of the stories and commentary provided by former players and former interviews are worth the 60 minutes each week. I especially loved West Texas' own Sammy Baugh talking about the old Polo Grounds and why he is anti-cities ("That's why I'm a country boy...I can go outside and take a leak whenever I want").
2 other quick interesting stories:
Abner Haynes ("We kick to the clock") was originally drafted by Pittsburgh. Haynes told the story of Bobby Layne and Buddy Parker showing up at his house at 5:30 in the morning, both so drunk they could hardly stand. They cheerfully informed Haynes the Steelers we drafting him. Haynes' father, a minister, immediately let his son know that he would not be playing for the Steelers. After meeting Lamar Hunt Haynes ended up with the Dallas Texans.
The Dallas Texans and Dallas Cowboys were both fighting for supremacy for fans (you were either one or the other). The Cowboys often played on Friday nights (as did all the high schools), so Lamar Hunt and the Texans ran a promotion if a fan would bring a ticket stub from a high school game they'd get into Texan games for free.
Also, for those that are impatient and want to know everything immediately you can visit http://www.remembertheafl.com/AFL.htm.