Gravity Probe B http://einstein.stanford.edu/
Gravity Probe B is the relativity gyroscope experiment being developed by NASA and Stanford University to test two extraordinary, unverified predictions of Albert Einstein's general theory of relativity.
Gravitational Waves: An Introduction http://arxiv.org/abs/physics/9908041
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.