VRML is by now the most diffused standard language for 3D world models on the Web,

X3D is an open standard for 3D content delivery. It is the next revision of VRML. X3D files can be displayed with a X3D plugin, program, or toolkit. Most of the X3D plugins also display VRML files. X3D has been approved as an ISO International Standard. VRML models can be converted to X3D with the VRML to X3D translator.

Look at a sample VRML or X3D model for your browser compatibility.

A small world model archive here