How do you access the NFL's API's?

While I haven't had any success with api.nfl.com, I am able to get some data from the api.fantasy.nfl.com. You should have read access to all of the /players/* endpoints (e.g. http://api.fantasy.nfl.com/v1/players/stats?statType=seasonStats&season=2010&week=1&format=json). I would think you need an auth token for the league endpoints and the write endpoints.

How long ago did you email them?

EDIT: I emailed the NFL and this is what they had to say: "We've passed your API request along to our product and strategy teams. NFL.com Fantasy APIs are available on a per-use, case-by- case basis for NFL partners. Our team reviews other requests, but our APIs are typically not available for external usage otherwise."