OurWorld - OurWorld is an Action, Great Online Virtual World, Social Interaction, MMO, and RPG Simulation by Flow Play.
Second Life - Second Life is a virtual reality platform where individuals interact in a virtual world. The software was developed in 2003 by Linden Labs. More than one million people now regularly use the software.
YoWorld (Yoville) - YoWorld or formerly known as Yoville, is an Action, Browser-based, MMO, RPG, Single-player and Multiplayer, Social networking, and Virtual World Simulation developed by Big Viking Games.
Movie Star Planet - Movie Star Planet is an Online Virtual World, MMO, and RPG Simulation by MovieStarPlanet.
MySims Kingdom - MySims Kingdom is based upon The Sims series but provides special and extremely different gameplay to the original series making it definitely worth your consideration.
The Legend of Pirates Online - Pirates of the Caribbean Online is an Action MMORPG, Exploration, Virtual-World, and Exploration Simulation developed and published by Disney Online.