If it becomes standard practice to have referrals in Test cricket, which I hope it doesn't, because it slows the game down and robs us of the pure exhilaration of a wicket falling, I can see a couple of interesting consequences arising:
Umpires will be judged on how often their decisions are referred and, crucially, their "turnover rate", which could prove rather a stark assessment of their quality.
Bowlers too will eventually build up a record in this area. Will it demonstrate how respected a bowler is by his captain? If Jimmy Anderson gets more decisions referred over time than Stuart Broad, surely that implies something about Andrew Strauss' opinion of his judgement?