Well, it's ATI again. They just released an updated version of their Radeon-SDK which has grown much bigger since the last (July) release.

It weights in at 340 MBytes (that's almost 200 MBytes more content than the last release) and finally comes with a handy SDK-browser (guess they learned something out of NVidia's great SDK ). It includes content for both APIs, DirectX and OpenGL. You'll find samples, documents, tools and some more stuff in. So if you do some advanced graphics programming, grab it and take a look at brand new stuff like FBO, HDR. (Note : Most of the demos need brand new hardware)