arXiv.orgFull-text primary literature of computing and computer science published by Association for Computing Machinery (ACM); from 1954 to present
CERN Document ServerA source for particle physics and related areas, this site includes the bibliographic records and full-text of preprints, articles, books, journals, photographs, and much more. CERN is the European Organization for Nuclear Research and the world's largest particle physics center.
ComPADREThe AAPT ComPADRE Digital Library is a network of free online resource collections supporting faculty, students, and teachers in Physics and Astronomy Education.
Eric Weisstein's World of Physics"Online encyclopedia of physics terms and formulas. Full searchable, and also browsable alphabetically and by topic. Part of Eric's Treasure Troves of Science."
Kahn AcademyKhan Academy is a set of 1000+ videos covering everything from basic arithmetic and algebra to differential equations, physics, statistics, chemistry, biology and finance. Includes SAT and GMAT prep.
SAO/NASA Astrophysics Data System"The SAO/NASA Astrophysics Data System (ADS) is a Digital Library portal for researchers in Astronomy and Physics, operated by the Smithsonian Astrophysical Observatory (SAO) under a NASA grant. The ADS maintains three bibliographic databases containing more than 12.2 million records covering publications in Astronomy and Astrophysics, Physics, and the arXiv e-prints. Abstracts and full-text of major astronomy and physics publications are indexed and searchable through the new ADS "Bumblebee" interface as well as the traditional "Classic" search forms. A set of browsable interfaces are also available. "
Science.govScience.gov searches over 60 databases and over 2,200 scientific websites to provide users with access to more than 200 million pages of authoritative federal science information including research and development results.