A little while ago I heard about a MMORPG in development called Riders of War. Apparently it's a 3D fantasy MMORPG where you start with a mount and customise it and stuff. And most combat is done on it. And you can buy heaps of cool new mounts and stuff. I heard you pick a species of mount at creation like wolves, horses, felines, mammoths etc. And thats basically your class, with mage, warrior and that as your secondary class. And something that seems cool is that the highest ranking player from each of the four factions will own there factions dragon as a mount. There're changing sites now, so when I find the current one i'll post.