Goal line... they need a 3rd ref, watching a video monitor. Referee in doubt goes to his decision. People say it will slow the game down, but let me tell you, it won't slow it down as much as the rolling around feigning injury, or the constant appealing of decisions players do. It will also put all doubt aside, and hopefully those wankers on talkSPORT are lost for words. If a heavy malicious take or 'barton' happens, the referee puts the player on report, and the issue is dealt with by the FA within a week after the match. Using a panel of transparency and professionalism (probably need to restructure the FA haha).
I'm not saying, go as far as the NFL, but have a look at how the NRL disciplinary system works, as well as in-game ruling.