Somebody posted this in another thread. Might be worth the investment in your case.
http://www.amazon.com/PS3-Move-TV-Cl...4665368&sr=1-1
If you don't want to spend that much on a solution, you could always go to any hardware store and pick up some velcro adhesive strips. Stick one piece on the TV and one piece on the bottom of the PS Eye. However, it should be noted that the adhesive may leave residue on the top of the TV if you ever decide to remove the strip from the TV.
My TV is high enough that I have my centre channel speaker mounted on the wall directly below it. So, my PS Eye sits on top of that no problem. The bottom of the PS Eye definitely has a no-slip type of surface, but it isn't perfect.