The Goddard Library - Information in engineering, space and physical sciences, and earth sciences. Go here for patent and standards information, web links, and government information.
Lawrence Berkeley National Laboratory Library - Part of the Technical and Electronic Information Department (TEID). The "pathfinders" section includes links to a wide range of information for chemistry, biology, physics, materials science, engineering, and so on.
Oak Ridge National Laboratory Research Libraries - "Science & Technology Guides" on a wide range of topics, including consumer health, robotics, transportation, and pure sciences. Also, links to "Reference Resources" such as maps, patents, and conferences.
Redstone Scientific Information Center - A comprehensive scientific and technical library serving researchers and engineers at the U.S. Army Aviation and Missile Command, NASA Marshall Space Flight Center, and their contractors.