I have seen some big numbers in my gym, but i think the most impressive was a 140 kilos (300 lb more or less?) bench press for 6 reps...
I know, this may not seem so big, but have in mind that the guy who did it weights like 130 lbs, and has like 5 foot...He is very cut, so a lot of his weight its muscles, but he is very small, given his height...
For sure, pound per pound, the most strong guy i have seen (he has some other strong exercises too, leg presses, military presses, barbell rows...etc...)