You shouldn't use a wrist rest while typing, because of bending wrists. You probably shouldn't use a wrist rest at all, because of pressure on carpal tunnel. Moreover, I'd never use a wooden/plastic/metal/leatherette/leather one, because of usually cold surface.
I occasionally rest my *palm* on Allsop Wrist Assist, while navigating through a document. I've considered the Grifiti fat one for gaming, but again—I want to refrain from using anything like that.