Coolit is working on some really cool , self contained water gpu loop systems.
You buy it , its comes with a universal cooper block that the water loops through. You purchased individual custom 'interposer' plates for 'popular' video card models. You bolt on the interposer plate to your GPU, chips+mem and mount the sealed copper water (piggyback)block and your done. Thats how I believe it works. You never have to open the system.
http://www.youtube.com/watch?v=GzQZ7SLnHoo
edit: If they ever brought this to market at a price , similar to what the cpu closed loops cost, it would be awesome. More copper and a extra plate, so I figure 150.00 VS 80 for their cpu 120mm loops.