This study from PredictionMachine.com attempts to estimate the home field advantage of each FBS school, in terms of points. It's interesting data, though not without some caveats, which are outlined in the article. Go on and read it; I'll wait.
These numbers can be a measure of consistency (or the lacktherof) as much as anything else, which is how a national power with a big, loud stadium like Florida State can end up dead last. In the Seminoles' case, it's a compliment, in that this is basically saying that FSU is so good, the venue has little impact on its average performance level.