muffins did some great work for Civ 3 - though unfortunetely the unit making process got very tedious very fast for that game (patching together several hundred static images to make an animation) meaning that there were never really enough for the Warhammer mod which was under construction to take off. Most of these models would require a small amount of conversion to reduce the polycount (by a factor of about 10 - these guys have awsome detail!)
My currently plan is to do some conversions from the RTS game "Dawn of War", as all of those models should be sufficiently low poly as to be workable in Civ 4, and to make my own models (or convert from muffins' models) for units not in that game.