Basically an HC bonus whenever you kill a player with a killstreak. The longer you keep the killstreak, the greater the hc bonus for your hunter. Per server or universal, I think it would add some spice to your everyday matches and encourage the newbies to go for one more kill.
I'm guessing something like this would float around 25-100hc per kill, maybe up to 250 or 500 hc. Either way, I'm pulling these numbers out of my fuzzy bunny but I think it would be awesome.