One of the hardest accessory questions to answer is, "Should I spend more for a really fast card for my camera?" Only Rob Galbraith knows for sure, because he has the time to test them all. But he kindly packages the results in a neat database so you can see how well a particular card performs in your camera.
Rob's just added results for the Canon EOS 50D, Nikon D90, and Sony DSLR-A900. Unsurprisingly, in newer models, the SanDisk Extreme III Ducati cards seem to be the fastest CF cards across the board, and the Extreme III 30MB/sec edition takes the SD crown.