5 links
OpenGL Relativistic Spacetime Project
spacetime.sourceforge.net
A real time relativity simulator for Windows, Linux and OS/2, using OpenGL.
Relativistic Ray Traced Images
fourmilab.ch
Features visualization of relativistic deformation effects of a spaceship like object.
Relativistic Starflight
hexadecimal.uoregon.edu
The program xrel depicts, as realistically as possible, the appearance of stars as seen from a starship moving at speeds close to the speed of light.
The Cactus Code
cactuscode.org
A modular manageable high-performance 3D tool for Numerical Relativity.
Warp Special Relativity Simulator
adamauton.com
A windows program to show you the weird effects of special relativity.