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.
Neopets - Neopets is an Amazing, Virtual World, Massively Multiplayer Online, Role-playing and Fantasy-based video game developed and published by Viacom.
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.
Toontown Rewritten - Toontown Rewritten is a Free to Play, Browser-based, MMORPG, and Virtual-World video game developed and published by Disney.
OurWorld - OurWorld is an Action, Great Online Virtual World, Social Interaction, MMO, and RPG Simulation by Flow Play.
Webkinz - Webkinz is an Animal-based, Virtual Children’s World, Fantasy and Browser-based Simulation developed by Ganz.