Football research suggestions

What are some good site recommendations to use for statistical research?

I'm interested in seeing what some of the folks on this board gravitate towards for crunching the numbers. I'm assuming you can find more detailed stats if you're willing to pay for them most likely, but are there free options out there that are better than others?

This FanPost was created by a registered user of The Daily Norseman, and does not necessarily reflect the views of the staff of the site. However, since this is a community, that view is no less important.