BRL-CAD is a powerful constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, network distributed framebuffer support, and image and signal-processing tools.
Terraform allows you to create fractal terrain (also called a height field) and transform it using a number of algorithms. It is meant to be a tool for those who want to generate digital terrain models for use in raytracing or other simulations. Terraform features different views and colormaps and has a preview mode which features interactive real-time rotation of the terrain object. Terraform is written for the GNOME desktop environment.
WireFusion allows interactive, plug-in free, and very compact Java presentations and product simulations to be created for the Web. Development involves visually connecting preprogrammed objects or by coding in Java. Several add-ons are available, including a real-time 3D engine where textures can be replaced with interactive 2D presentations, an MPEG video player, a slide show viewer, and an MP3 player.