4th Down Calculator feature here at AFA. It uses both the Expected Points model and the Win Probability model to estimate the best option for every 4th down as a game is in progress.
As I mentioned last year, although the 4th down issue is growing mold with smarter fans, it remains the lowest hanging fruit on the football analytics tree. So it's nice to be able to automate things and not have to do the analysis myself. But on the other hand, we can add 'football analyst' to the list of jobs being taken over by robots.
The Bot will be faster, more accurate, and come with some new features this season. Here is a brief introduction. Here's are a few notes on how it works. And here is his Twitter feed.