HEASARC - NASA's High Energy Astrophysics Science Archive Research Center
Infrared Science Archive - NASA's science and data center for infrared astronomy
Extragalactic Database - NASA's archive of data for over 3 million extragalactic objects
National Virtual Observatory - Astronomical data from ground and space-based telescopes. Includes data analysis tools
National Space Science Data Center - Archive for NASA space mission data
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 9.1 million records: Astronomy and Astrophysics, Physics, and arXiv e-prints.
Cambridge Structural Database - small molecule crystal structures
eCrystals - x-ray crystallographic data
PubChem - NCBI's repository of bioactivy/bioassay data and information for "small" molecules (i.e. not macromolecular). Both text-based and structure-based search tools are provided
ChemSpider - free-to-access collection of chemical structures and their associated information
CodePlex - provided by Microsoft
GitHub - Hosts developer libraries such as Ruby on Rails, IronRuby, jQuery, Perl
Google Code Project hosting - open APIs and Google projects like Google Gears, Android, Chromium.
Launchpad - includes projects such as Ubuntu, MySQL (code hosting)
Cooperative Association for Internet Data Analysis (CAIDA) - Archive of data for scientific analysis of network functions