ive seen one every now and then, but someone needs to put together a quality pack of them.
ambient sound tracks. you know the basic stuff;
water
rushing water
windy area
non descript crowd of people talking / town-like sfx
basic woodland forest sounds
rain forest
and whatever 30 more.
i say the pack must be of decent size, so it would be more of a common must have download, rather then have odd files people must dl on server join, or miss out on.