This is some of the work I've done with the Virtual Reality Markup Language (VRML 97). Although VRML never quite fully caught on, it's an extraordinarily simple and powerful way to create interactive three dimensional visualizations.
See the help below to make sure your browser can view these worlds.
A rotating planisphere with the 88 celestial constellations.Screenshot Examine the Earth and Moon from various perspectices. Demonstrates phases of the Moon and Earth.
Screenshot View a schematic of an annular eclipse.
Screenshot Mars with its moons Phobos and Deimos.
Screenshot Attempt to diagram what a pulsar looks like.
Screenshot Welcome to Smiley's! Fresh Java! Open 24 Hours!
Screenshot What causes the seasons? Demonstrates interaction between VRML plugin and Java applet. Rotates a model of the world (time zone map) to look at input location (name or latitude/longitude). Your VRML plugin must support the EAI specification (most do) and Java applets.
How to view this content
To view these "worlds," a VRML browser plugin such as Cortona, Cosmo Player, or InterVista WorldView is required. Cortona is the most advanced, Cosmo is a high-quality alternative, and WorldView is a fine medium-quality plugin (although Internet Explorer only).
Click the link above to test your VRML plugin. If the plugin is installed, but you see a black or blank area with no content, try "enable software rendering" (look in the plugin's documentation).
UNIX users may have to do more work. The OpenVRML developers have a very nice, fast browser called lookat that implements most of VRML97. The screenshots here are from lookat running in KDE. It can also function almost like a plugin using XSwallow. Or, you may have better luck with one of the other open source VRML browsers.
What happened to VRML?
I think the lack of a great cross-platform plugin for VRML was the single biggest reason why developers didn't flock to it the way they did to, for example, Flash (which has no true 3D support). And without the content, users didn't adopt VRML plugins (though for a short period when it was a buzzword, Netscape came installed with the Live3D plugin and Microsoft offered WorldView from the WindowsUpdate page. Finally, by the time hot 3D graphics cards became the norm, the buzz had died.
It never became integral to the web experience, remaining in a niche. But it still has its uses, and is quite fun to program. You can learn the basics of VRML in a few hours to a day, and be coding up high quality 3-D animations with nothing more than a text editor.