I for one am happy for a single slot solution. I only have 3 PCI ports below the PCI-E one and the dual slot cooler ends up covering two of them.

Even though I have my sound card at the most bottom PCI port, the cooler-heatsink is like 1/2 an inch from my soundcard and it's ridiculously hot and I smell a slight burning tinge, lol. Can't wait to return my 320mb Fata1lty 8800GTS and pick up an 8800GT with single slot cooler, plenty of space for my PCI cards to breathe =)