Although you can share data just by posting it on your website, by using a trusted or even certified repository, you will make your data discoverable and citeable. There are general and domain-specific repositories. A few common ones are listed below:
Domain Specific Data Repositories
Note: Not all of the repositories listed can ensure long-term preservation of your data; contact each one for more details. For a more repositories, see on of the resources on the right.
Astronomy
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.
National Space Science Data Center - NASA's permanent archive for space science mission data.
Atmospheric Science
National Center for Atmospheric Research - The CISL Research Data Archive (RDA) contains a large and diverse collection of meteorological and oceanographic observations, operational and reanalysis model outputs, and remote sensing datasets to support atmospheric and geosciences research, along with ancillary datasets, such as topography/bathymetry, vegetation, and land use.
Biology
BCO-DMO - The Biological and Chemical Oceanography Data Management Office provides access to data sets contributed by investigators funded by the Biological and Chemical Oceanography sections of the US National Science Foundation (NSF).
Dryad - Dryad is an international repository of data underlying scientific and medical publications, particularly data for which no specialized repository exists. All material in Dryad is associated with a scholarly publication. Most data in the repository are associated with peer-reviewed articles, although data associated with non-peer reviewed publications from reputable academic sources, such as dissertations, are also accepted. Dryad is a non-profit organization.
Genbank - GenBank is an annotated collection of publicly available DNA sequences available through the National Center for Biotechnology Information databases. GenBank contains over 135,000,000 sequence records and is updated every two months. GenBank is part of the International Nucleotide Sequence Database Collaboration along with the DNA DataBank of Japan and the European Molecular Biology Laboratory.
Chemistry
PubChem - provides information on the biological activities of small molecules. It includes substance information, compound structures, and bioactivity data in three primary databases, PCSubstance, PCCompound, and PCBioAssay, respectively.
Computer Science
Cooperative Association for Internet Data Analysis (CAIDA) - provides tools and analyses promoting the engineering and maintenance of a robust, scalable global Internet infrastructure.
Oceanography
National Oceanographic Data Center - NODC is an organization made up of the Oceanographic Data Center, National Coastal Data Development Center, World Data Center for Oceanography, and the NOAA Central Library, integrated to provide access to the world's most comprehensive sources of marine environmental data and information.
Social Sciences
Inter-university Consortium for Political and Social Research (ICPSR) - ICPSR is the world's largest archive of digital social science data. ICPSR staff can guide you in preparing your data for archiving and distribution.
IQSS Harvard Dataverse Network - One of the world's largest collection of social science research data.
