High speed flash cards, high capacities and only three major companies have them. 300x compact flash cards are the fastest in the market but there are not many who make them. The cream of the crop can be found in this article.
The Transcend Extreme Speed 300x CompactFlash card is one of the fastest available in the market. It is designed specifically for professional photographers but the CF card can be used with anything that is compatible with it. Since it supports Ultra DMA mode operation, it can support very fast transfer speeds of up to 45MB/s. DMA stands for Direct Memory Access which allows the CPU to operate more than one function at a time during data transferring. In a sense, having Ultra DMA would speed up the flash drive because the CPU doesn’t have to copy each piece of data from the source to the destination.