I really enjoyed Divine Divinity which is diablo style. It's basically like diablo, except with a much better story driven experience. No idea on whether there is multiplayer though.
Sacred is also similar though I didn't find it as good. I think this one has multiplayer.
The problem is, none have the closed, anti-cheater online play like diablo 2. So if you just want the same style gameplay, I recommend Divine Divinity