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.
Neopets - Neopets is an Amazing, Virtual World, Massively Multiplayer Online, Role-playing and Fantasy-based video game developed and published by Viacom.
Movie Star Planet - Movie Star Planet is an Online Virtual World, MMO, and RPG Simulation by MovieStarPlanet.
Animal Jam - Animal Jam is really a virtual world for kids that includes real animal and plant information towards fun storylines which are maintained by National Geographic educational content.
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.