Argus - Collections management for museums & galleries
Toontown Rewritten - Toontown Rewritten is a Free to Play, Browser-based, MMORPG, and Virtual-World video game developed and published by Disney.
Meow Playground - Imagine Club Penguin with cats!
Neopets - Neopets is an Amazing, Virtual World, Massively Multiplayer Online, Role-playing and Fantasy-based video game developed and published by Viacom.
CPPS.io - CPPS.io is a clone of Club Penguin, you will have the same experience as if Club Penguin was still around, with free membership custom features and more, come join CPPS.io a great alternative to Club penguin.
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.