I've had this discussion with people a few times and it's always interesting to see the answers. Give your nominations and some supporting evidence.
I'll start with one of the slightly less obvious choices. Steve Smith continues to amaze me on a regular basis. Hes like 5'9 and 185 yet constantly comes down with balls he seems to have no business catching. Imagine if this guy had one of the elite QBs in the league throwing him the ball?