DS3 is fine, or you can get a 3x PCIE slot Badaxe like me....then you can get physics cards, graphics cards....
I think they will start brining all wifi, sound cards etc to PCIE eventually..not sure what benefits would come of it though.
BTW, the 8800 series takes up two slots, that does not mean it has to make two seperate pcie connections. It just means that its really fat and big and needs space inside your case.. dont expect to put anything in the adjacent slot.