I have to agree, the 8800 GTX had more than the 2x the performance of the 7900 GTX and unified pixel/vertex shaders were such a good idea that we still use it today.Wait... greatest GPU of all time?
After that I think the GTX 460 was one hell of a GPU for $230. The stock speed was 675 MHz and people were routinely hitting 850 MHz with a little bit of extra voltage. Mine topped out at 875 MHz. Nowadays you cant overclock anything that high from stock speed.