I've seen refs go to the TMO to see if a drop goal or Penalty has gone over, where it's been to close to call. Some refs need to grow a pair though, some tend to ask the TMO on every try! One of the reasons I like Nigel Owens, even if he does get some calls wrong, atleast he calls most try's without the aid of the TMO.

Also, why do TMO's always take so long?