I have some figures, although I don't know where they came from, which say that: -
96% of guys are under 8"
3% of guys are between 8" and 9"
1% of guys are over 9"
Some other figures I have say that 1 guy in 100,000 are over 11". Yet others state that 1 guy in 20,000 is 4 standard deviations above the mean, which works out as being 10.25"
I guess there will always be a lot of discrepancy in any figures as they're usually based on either a very small sample or a very unrepresentative sample. If anyone plans a bigger survey I'd be happy to get my measuring tape out ;-)
cheers
Dillon