Well from what I know, there arn't any other. However, you can look forward to World of Midgard, which of course, might be a long way before it is released.
Dont think there are any others, i know you wanted an online one but make sure you check out Aralon. Bit like an offline Order & Chaos, epic huge RPG, this game had me hooked for weeks and weeks
Yes, just one other one: Conquer Online http://forums.toucharcade.com/showthread.php?t=115430 Just got released. Same MMORPG game that's on the PC/Mac
Parallel Kingdom is, strictly speaking, a location-based MMORPG. However, the gameplay and graphics aren't anything like Order and Chaos. It makes sacrifices therein due to its location-based nature, but it's interesting in its own way.
Yeah, what was mentioned is pretty much it! However, World of Midgard is supposed to be hitting the AppStore 1st quarter of next year, if I'm not mistaken. I think WoM will definitely be the new standard for MMORPGs once released. http://forums.toucharcade.com/showthread.php?t=94153
I forgot about Yslandia, and I'm downloading The World of Magic now! Wonder how I missed that game, oh well! Thanks!
Celtic Heroes is an open world full 3D MMO on iPhone/iPad/iPod, it's a free download from the app store: http://itunes.apple.com/app/id431837446