Benchmark Reviews posted a howto about overclocking the NVIDIA GeForce 8800 Series

NVIDIAs 8th generation of video cards brings a new dimension to overclocking with the new shader clock. Although this how-to guide covers all recent NVIDIA video cards, I have selected the FOXCONN NVIDIA GeForce 8800 GTS as my test subject. Presently, the 640MB version of the GeForce 8800 GTS is the second-best video card available on the market. Gamers and computer enthusiasts alike have already speculated on how the GTS could be made to perform to the same level as the GeForce 8800 GTX with some tweaking. Learn how to take a great product and making it even better; and do it all for free.

How to Overclock the NVIDIA GeForce 8800 Series