If you haven't heard of this yet, Path of Exile is basically a Diablo-like, isometric ARPG (action RPG) with online components. UNLIKE Diablo, it's completely free to play. I was really impressed with what the relatively small development team at Grinding Gears Games did with PoE in terms of gameplay and presentation. It doesn't LOOK like a free to play offering - it looks like something you'd pay for.
http://www.pathofexile.com/