I was checking out the Crystal Space 3D site (the engine behind Planeshift, an MMORPG) and projects using the Crystal Space engine. I came across a project named Festonia which aims at creating a world wide 3d web. The project has released the first 0.01 alpha version of the 3d browser, and as per the site is supposed to be in testing (didn’t find it for download though). The project seems to be aimed towards providing ways to setup 3D web servers for 3D websites. This probably makes it somewhat different from Secondlife, though a 3D web could very well take the form of Secondlife which has facility for content creation, ownership and its own economy.