You can find incomplete lists in a variety of places, the IGN faction previews give you the information on a few factions units and the demo gives you everything on the French, English, HRE and Spain(well at least most of their later era units). The Sega site gives you images, but as far as I know there is no complete list, partly because we have no idea what a lot of factions will have i.e. The Aztecs and the other new factions and many of the factions from MTW might have changed.