Open 3D Scientific Visualization Toolkit
Mark Leaman writes "The Science Museum of Minnesota has just announced an online community site for scientific visualization, including thier Open 3D Visualization Toolkit that includes Blender and the GIMP as part of the core development tools. Frustrated with a lack of consolidated resources and discussion about open-source, scientific visualization development tools, the Science Museum of Minnesota's Learning Technologies Department decided to develop their own."
Maybe you should give VTK, OpenDX, VisIT or Paraview a try, all of which are just some of the scientific visualisation community's tools of choice (and hey, they're OSS, mostly cross-platform as well).
You should take a look at VPython -- Simplest 3-D visualization that I know of (and it runs on Windows, Mac, and Linux).
http://www.vpython.org/
This the point where I remind people of OpenDX, which is the open sourced IBM Visualization Data Explorer. DX used to be an extremely expensive commercial product, but it's been open source for a couple of years now.
It's very good. If you're into scientific visualization it's worth examining.
Proprietary? VRML is an ISO/IEC standard.
As far as NASA planetary datasets go, try the Planetary Data System
Some of the USGS topo datasets are available from the EROS Data Center. Some free datasets are available for download.
Open-source Visualisation software:
Counter-examples:
Scroogle
I think OpenDX is a bit more than just a tool-kit. It also has a great GUI for doing visualization, without the need for too much coding (somewhat analagous to LabView, I suppose). I have found I really like MayaVI, which is a GUI for VTK. MayaVI/VTK are python scriptable, which is great.
Actually there is an open viewer for molecules. It's called Rasmol http://www.umass.edu/microbio/rasmol/ and many source files can be downloaded from their site.