As Nickelodeon continues its gaming and virtual world expansion, we have some more details about the three virtual world sites now in development and plans to introduce a choice of paid subscriptions and advertising for its existing 2.5D online city Nicktropolis.

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Nick is creating a virtual world around its Neopets social net site that carries the working title of World of Neopia. Existing animated property SpongeBob SquarePants is also getting its own virtual world, while the other planned community is tentative called Monkey World. To further drive home the increased significance of creating virtual environments, its NeoStudios is now the Nickelodeon Kids and Family Group Virtual World Studios. Monkey World and the SpongeBob virtual world are both in the conceptual stages of development..

In early 2009, Nicktropolis users will be offered a paid layer with premium items, avatars and games, in addition to the site’s free-to-play mode. The new worlds from the Virtual World Studios will also operate under hybrid business models, with ad-supported free-to-play and paid subscription levels as well—and will sell virtual goods.

—And For Adults, Paramount’s Virtual World Play: Nick’s Viacom (NYSE: VIA) sibling Parmount Digital Entertainment is employing popular social net app VooZoo to let users of adult-focused virtual world There.com to send short clips from movies and TV shows.  Clips will be available for There.com users to buy for $1.00 each. Secondly, MTV Networks will offer clips from its pop culture shows available to There.com users as well as on it its virtual world, vMTV. The VooZoo app is currently in private beta in There.com (the app is also on Facebook) and will be available some time in Q2 in vMTV. Release