http://www.nfl.com/news/story/0ap1000000129783/article/will-firstdown-line-arrive-at-an-nfl-stadium-near-you

Apparently, a company is working to implement a laser system that will show a first down line at NFL stadiums. It would be cool to have a better idea of what’s going on at the stadium, but what if the line is off, and a player goes for the line and doesn’t get the first down?