I've been doing a bit of PVP on my DK lately, and I found a little trick in Warsong Gulch that I love pulling off. It's not a game-winning move or anything, it's just fun.
As everyone knows, the Warsong graveyards are atop small hills overlooking the open central field. When a player dies, they will usually resurrect, mount up, and ride off the hill towards the opposition base.
It's a simple yet effective trick. First of all, I get in a few hits before they even realize what happened. Secondly, if they're ranged, they are stuck in this tiny little crevice with me, and the angle/tight quarters makes it hard to blink or disengage to safety. Third, since they are moving forward when I grab them, and because it's such a short-range, fast death grip, they likely kept moving forward and are now riding their mount straight up a wall, completely messing up their camera and perspective.
Obviously, you can only do this a few times before a handful of enraged Alliance pour down the slope and murder you. But it's a funny way to get a few kills, and if you're distracting a few opposition players from defending their flag or grabbing your team's flag, it's well worth the effort.