This is the wet dream of all serious user of digital photography cameras (or similar mobiel devices for digital music, portable movies, portable video game consoles). But it is very difficult to find a real comparison with real products. Well! This is what the excellent Dyxum.com web site offers in an extensive comparison of Compact Flash memory cards (and some SD cards, too).
Personally, I conclude from reading it that Sandisk and Lexar build very fast cards (but very expensive ones!). I noticed that Transcend who builds very low cost cards reach an impressively high level of performance and so offer a nearly unreachable performance/price ratio.