Open Access

The Directory of Open Access Repositories - OpenDOAR
Registry of Open Access Repositories - ROAR
ROAR allows users to search or browse more than 700 OAI-compliant open-access eprint archives. Cover OA content (full-texts) of preprints, postprints of peer-reviewed journal articles, or dissertations. Allows browsing by Country, Archive Type, or Archive Software. Also tracks the growth in OA archives (the number of records in each archive, across time), showing growth charts for each Archive, as well as across Archives.(Introduction by the Library of Congress)
Directory of Open Access Journals - DOAJ
  Directory of Open Access Journals service covers free, full text, quality controlled scientific and scholarly journals. DOAJ aim to cover all subjects and languages. There are now 2727 journals in the directory. Currently 823 journals are searchable at article level. As of today 137739 articles are included in the DOAJ service.
Open Access English Language Journals Portal - OPEN J-Gate
  Open J-Gate is an electronic gateway to global journal literature in open access domain. Launched in 2006, Open J-Gate is the contribution of Informatics (India) Ltd to promote OAI. Open J-Gate provides seamless access to millions of journal articles available online. Open J-Gate is also a database of journal literature, indexed from 4000+ open access journals, with links to full text at Publisher sites.
HighWire Press
A division of the Stanford University Libraries, HighWire Press hosts the largest repository of high impact, peer-reviewed content, with 1055 journals and 4,344,065 full text articles from over 130 scholarly publishers. HighWire-hosted publishers have collectively made 1,695,020 articles free. With our partner publishers we produce 71 of the 200 most-frequently-cited journals.
PubMed Central - PMC
PubMed Central (PMC) is the U.S. National Institutes of Health (NIH) free digital archive of biomedical and life sciences journal literature.
The Scientific Electronic Library Online - SciELO
  The Scientific Electronic Library Online - SciELO is an electronic library covering a selected collection of Brazilian scientific journals.
Reader Software

Reader Software Download
Portable Data Format (.pdf) Adobe Acrobat Reader
PostScript (.ps) Ghostscript, Ghostview and GSview
Zipped (.zip) WinZip
TeX (.tex) TeX Viewer
DjVu (.djvu) DjVu Viewer
Device Independent (.dvi)  PCTeX Reader
GNUzipped (.gz) WinZip
Taped (.tar)  WinZip
Microsoft Word (.doc) Microsoft Word Viewer
Other Format see Common Internet File Formats