Technology and locating the football.
In the last fifteen years, the NFL has reinstated the use of high frame rate instant replay, added video game-style camera angles, and worked with various apparel outfitters and rule amendments to speed up the game while increasing the safety of their players. There is one aspect of the game that remains deeply rooted in the 20th century: the use of chains to measure first downs.
North Carolina State University and Carnegie Mellon University funded by a grant from Disney Research has worked to find a way to more accurately track the position of a football on the field. Based on the nature of the game, the use of GPS or RFID to track the football would be inhibited by the bodies of the players. Researchers have since developed a series of low-frequency magnetic field antennae that can track the ball in three-dimensional space.
The technology is called the Magneto-Track System. The current status of the technology can pinpoint the ball to within one foot of its physical location. The current chain-based system is accurate to within six inches, however, this research looks promising.
For more information, check out this article from Vox.com.