NASA's Jet Propulsion Lab's PlanetQuest website is brilliant. This is a stunning proof of the power of X3D as an educational format that is beautifully surreal presenting complex information compactly. The techniques applied are ingenious but easy to use and comprehend. This is the professional level of multimedia web content production that X3D needs.
The Wirefusion production approach to integrating text, 2D and 3D is straightforward. They build one dominant object and explain it in the style of a product presentation. Each topic is presented in a mode perfectly suited to it so navigating it is childishly simple and enrapturing.
My only nit here is the sound is noisy. Streaming sound is still the biggest quality gap in the X3D. Multitrack sound streams that enable the spatial capabilities of real-time 3D such as proximity based mixing and soundFollowers aren't here. On the other hand, this sound is a vast improvement over what we had to use ten years ago so I am still blown away. Personally, loops bore me unless other sound nodes are used with them, for example, an option to have the text entries read by a human voice (not a synth). It only takes a little work to record the voices. I understand the bandwidth vs click through problems, but as a musician/actor, you can blame a guy for wanting. :-)
With only that nit, I recommend this site to anyone, but particularly to X3D authors and site designers as a to-be-studied example of doing it right.