The 8800GTS is huge man, its certainly longer than other cards like the 7900GT that I have. I personally think that the double slotted cooler is enough.
*EDIT 2* - yeh, this really is like the only one - http://www.svc.com/hr-03plus.html - good news is its passive (by the looks of it) not exactly wha ti would recommend for such a large graphics card but meh... Give it a few months for manufacturers to get their designs out and there will be plenty