ABC-Chemistry: The ABC-Chemistry Directory aids in locating chemistry journals that have free full-text availability. All the journals indexed are peer-reviewed.
arXiv--Pronounced archive, this site is managed by Cornell University and is funded by the National Science Foundation. It has over 700,000 pre-published articles in math, physics, quantitative biology, quantitative finance, and statistics.
Biodiversity Heritage Library: "a consortium of natural history and botanical libraries that cooperate to digitize and make accessible the legacy literature of biodiversity held in their collections and to make that literature available for open access and responsible use as a part of a global “biodiversity commons.”
Biology Open (BiO) "a journal that publishes rigorous, high-quality research across the breadth of the biological and biomedical sciences. We provide timely, thorough, constructive and fair peer review, with a focus on supporting researchers and reducing the pain to publish."
Bioline International: a "scholarly publishing cooperative committed to providing open access to quality research journals published in developing countries."
ChemIDplus: "Dictionary of over 370,000 chemicals (names, synonyms, and structures). Includes links to NLM and other databases and resources"
Chemistry Central: "an open access chemistry publisher, operated by BioMed Central and owned by Springer Science+Business Media, committed to the free and widespread dissemination of chemical research."
ChemSpider: "ChemSpider is a free chemical structure database providing fast text and structure search access to over 28 million structures from hundreds of data sources."
DSpace@MIT: MIT Open Access Articles contains scholarly articles written by authors who are connected with the Massachusetts Institute of Technology.
IENG International Journal of Computer Science "covers the frontier issues in the computer science and their applications in business, industry and other subjects."
Frontiers: "The Frontiers journals are an interdisciplinary series of open-access journal."
HighWire medical and science journals
Hindawi open-access medical and science journals
Information Bridge: "provides free public access to over 307,000 full-text documents and bibliographic citations of Department of Energy (DOE) research report literature."
OMICS Group: "OMICS Group International is an amalgamation of Open Access publications and worldwide international science conferences and events. Established in the year 2007 with the sole aim of making the information on Sciences and technology ‘Open Access’, OMICS Group publishes 300 online open access scholarly journals in all aspects of Science, Engineering, Management and Technology journals."
OpenGeoSci: "OpenGeoSci is a free, public map based interface that allows users to search for maps, cross sections, charts, tables, figures, and data from GeoScienceWorld publications. The goal of OpenGeoSci is to further aid researchers in discovery of relevant valuable assets for academic research."
PubChem: "PubChem is organized as three linked databases within the NCBI's Entrez information retrieval system. These are PubChem Substance, PubChem Compound, and PubChem BioAssay. PubChem also provides a fast chemical structure similarity search tool."
PLoS--Public Library of Science publishes 7 peer reviewed scientific journals including biology, medicine, and genetics
Science Direct: Elsevier publishes 56 open access journals.
Science.gov: "Science.gov searches over 55 databases and over 2100 selected websites from 15 federal agencies, offering 200 million pages of authoritative U.S. government science information including research and development results."
SpringerOpen: "Springer’s portfolio of over 100 peer-reviewed fully open access journals across all areas of science ranging from very specialized titles to SpringerPlus, our interdisciplinary open access journal that covers all disciplines."