I have a Leadtek A6600GT agp. Its fast and I love it. Only thing.... the Ram it uses is rated to run a little above 1Ghz. It comes out of the box at 900Mhz. Idle my card runs at 38-41 Degrees Celcius. The RAM is a little under the heatsink so i can put on after market heat sinks. I would like better cooling tho. I have looked around but i CAN NOT find after market heat sink fans for the 6600GT series. Here is a pic of my card

Zalman VF700LED ?

You might try one like this.

http://www.newegg.com/Product/Product.asp?Item=N82E16835118117

One review says a guy used it for a leadtek 6600gt, so that's a good sign. Not sure if agp 6600gt's have a different heatsink mounting hole pattern than the pci-e ones or not. Several reviewers used it on agp 6600gts though, so it should work fine.
An all Cu(copper) heatsink is better than an AlCu(aluminum and copper), but both work well.

Alright, awesome. thanks!

Yes they do as the AGP has an extra chip on the PCB (HSI chip) that converts PCI-e connections to AGP. That's why there are two heatsinks on the AGP version, the HSI chip also needs to be cooled.

Ok, My HSI chip has a new coat of Artic Silver 5 and so does my GPU. they read 4 degrees cooler :grinthumb