I think I have a new favorite blog. It's Advanced NFL Stats by Brian Burke, who I've mentioned before. I've not seen anyone put out quality work like this guy does, statistical analysis just seems to come easily to him. He's taken papers published by economists and statisticians about football and found serious flaws in them and has followed up with better analysis. Every question I think of asking about the game he's already looked at in-depth.
Every NFL and sports fan should look at the stuff on his site. His Passing Paradox series is brilliant.
He gets rewarded with a link on my sidebar.