We've done research on home field advantage in the past at Football Outsiders, but I haven't looked at it for a few years. Here's some good research by Robby Greer that backs up some of the findings we've made in the past, and some other findings made by others more recently. Among them: home field advantage is lower now than it used to be, roughly 2.2 points instead of 3 points. Greer also finds that while individual teams might have periods of elevated home field advantage, there's nothing sustained or predictive about this. This is what I've found in the past, except for Seattle. Seattle was the one team that seemed to have a real larger home field advantage. But Greer finds this also isn't true, or at least hasn't been true the last few years. So perhaps no team truly has a larger sustained home field advantage than any other. The other interesting finding here is that home field advantage seems to be lower for divisional games. I may have to study that one myself in the offseason.