Most of my cameras utilize Compact Flash (CF) cards. When you’re shooting lots of images, or capturing big files (D800), you want to be able to move data quickly. CF cards continue to gain speed (Lexar announced a 3333x CF card this week at CES). I currently have 16GB UDMA 7 CF cards (SanDisk Extreme), but there are faster ones out there if you’re willing to spend the money. While a fast card is certainly going to help you clear your camera buffer faster, I’ve found that the real speed gain comes on the image transfer side.