I first came across the Second Life tribute to Kingdom Heart's Twilight Town totally by accident in 2006, when I was randomly exploring the virtual world while giving a talk about it at a Creative Commons event in San Francisco. When it fully loaded, the audience gasped. It disappeared from the world for awhile (sad to say), but now it's back, and it's just as beautiful if not moreseo - watch:

Here's the official site. Direct teleport to the city here at this link.

There's also rules here for Kingdom Hearts-themed roleplay in the city, which are pretty elaborate -- such as: