ADDENDUM: I should also have noted in Link 12 another site, halfclip.dyndns.info , for further illustrations and descriptions.
There's an interesting section on this site on variations in foreskin length, as they occur naturally.
This guy's perception of what the most common foreskin length is (with some overhang) is a bit different from mine - I don't think most men have much overhang at all - though some certainly do!