I'm certain this is already in the works, but just in case it isn't...
In Goldeneye there was a very distinct body impact sound that could be heard when you shot somebody, it's not something the average person would really notice unless they were listening out for it. In any case if you don't know what I'm talking about
and listen for the sound of bullets hitting people, best heard when riddling someone with the Kf7.
Also, and I'm sure everyone knows what I'm talking about when I say ricochet sounds. Those iconic whizzing ricochet sounds that you hear in so many old western movies (as well as a few of the older bond movies if I recall correctly).
As far as sound goes, those are the only things I think GE:S is lacking from the original. It's interesting how subtle changes in sounds can really alter the atmosphere and 'feel' of a game. Even small things like footstep sounds. As we're on the subject, it would be very awesome in the future to hear some new footstep and physics sounds, particularly things like footsteps on metal, concrete ... and those wooden scraping sounds we've all heard a billion times in Source.
Well, that's all.