Subject repositories are subject orientated collections of open access e-publications from multiple institutions, which are free to users.
ArXiv provides access to more than 650,000 papers covering physics, mathematics, computer science, quantitative biology and statistics, with content going back to 1991.
CogPrints covers the cognitive sciences including psychology, neuroscience and linguistics plus some areas of computer science, philosophy and biology, as pertinent to cognition.
Initially this repository focused on DataBase systems and Logic Programming (DBLP), but its coverage has since been expanded to include other fields of computer science and it now contains more than 1.6 million publications.
E-LIS provides access to more than 11,500 published and unpublished papers in library and information science and is maintained by an international team of librarians.
RePEc (Research Papers in Economics) is a decentralised repository with links to more than 600,000 full-text working papers, journal articles and software components. It is produced by volunteers working collaboratively in 65 countries. There are three separate interfaces within RePEc: