Hopefully this hasn't been posted before, and I apologize if it has.
Essentially what happens is a very basic "wallhack" (or really, more of a floorhack ).
-To start, enable "Smart Pivot" in the camera options (if it makes a difference, my other options are shown below).
-Now find whatever surface you want to attempt to look through and stand on it. Below I'm right near the reagent vendor in the undercity (magic quarter).
-To set up the position, jump forward and at the same time pivot the camera so your looking upward at your character. This part can be tricky and you might have to try it a few times. When you succeed you will see the bottom of your pants, or in my case, up my dress .
-Now slowely pull your camera back (to make it view more horizontally) and the camera should dip into the ground. This allows you to see some things you wouldn't see normally.
Essentially, you're looking downward but the camera is located just below your foot level so you see under things. I find it a fun trick.
I haven't though of many practical uses for this, but I'm sure you guys can be creative (perhaps spy on people in BGs). This works in all sorts of areas, and different views can be obtained if you're mounted. And unfortunatly, it does not work with ornate spyglass.
-SuperHippo