As always, XU here bringing you the latest and greatest exploits (before they are nerfed).
The latest is the Sledge of Athskeleng – legendary item. If you drop a few of these down on the ground, mobs cannot pass them. Its like an invisible wall and they are stuck.
What good is it? Well as you can see from this video, they are trapped on one side, and you can simply attack them and get awesom loot. It lets you farm areas that are way above you in terms of difficulty so you get better loot.
Here is a video showing off how it works. And yes it works with the latest 1.0.3 patch.
Right now these are cheap cheap cheap on the AH, so get them while they are hot.