Ricci A Mathematica package for doing tensor calculations in differential geometry and general relativity.
NOVA Online/Einstein Revealed Profile of Albert Einstein, with additional teaching resources, Shockwave demonstrations, and animations of relativity concepts.
Gravitational Lensing A popular site with interactive demonstrations of gravitational lensing. The background material is at a graduate level
Shapiro Radar Bounce Test A two part overview of the Shapiro radar bounce test of general relativity. (The two parts consist of a section for normal people, and one for nerds)
Interactive Experiments in Gravity Try an experiment that illustrates the gravitational attraction between two objects or use a Java applet to understand how orbits work in strongly curved space-time.
Gravity of Gravity An experiment at the University of Washington seeks to determine whether the gravitational binding energy of an object generates gravity of its own.
The 5D Spacetime Consortium We are a group of physicists and astronomers working on a 5-dimensional version of general relativity.
Gravitational Waves: An Introduction This paper presents an elementary introduction to the theory of gravitational waves. This article is meant for students who have had an exposure to general relativity, but results from general relativity have been derived in the appendices.
Relativity Provides information on the history, experiments and paradoxes of relativity.
Dulkyn: Scientific Center for Gravitational-Wave Research Research includes detection of periodic gravitational radiation from relativistic astrophysical objects, investigation of infra-low-frequency variations of Terrestrial gravity field in the role of crystal growing and compound formation, and investigation of time variations of Terrestrial inertial field and the geophysical consequences.
