The two hottest places on my laptop are, with the open screen facing me, the top-left (the vent for the fan over the graphics card,) and the bottom-right (my hard drive.) I have found a few pads, but I would like some other peoples' opinions before I buy anything.
I should also mention that I have a 12-cell battery, which lifts the back of my laptop ~1 inch off the surface it is placed on.