Free, open source software for open access journal publishing is available for those wishing to start up new journals, for example, the Open Journal Systems (OJS) developed by the Public Knowledge Project and HyperJournal developed by volunteers, but now partially funded by the political science faculty of Pisa University. While OJS and HyperJournal are designed for academic publishing, they can be used by anyone; for instance there is a group of grade 8 girls in Vancouver, British Columbia, who use OJS to publish their own peer-reviewed journal.
A repository is different from a journal. It includes peer-reviewed journal articles from many journals self-archived by their authors, as well as other kinds of material. Most repositories are distributed, institutional and cross-disciplinary, and some are central, cross-institutional and discipline-based. Here are some examples of central, discipline-based repositories (For Institutional Repositories, see Registry of Open Access Repositories (ROAR).
ViXra: similar in spirit to arXiv, but more accepting of less-established ideas (central)
CogPrints: Cognitive Sciences OA Archive (central)
Citebase: Citation-linked browser (harvested from distributed websites)
Citeseer: Computer Science (harvested from distributed websites)
OpenMED@NIC: An open access archive for Medical and Allied Sciences
PubMed Central: the U.S. National Institutes of Health (NIH) free digital archive of biomedical and life sciences journal literature
Research Papers in Economics: a collaborative effort of over 100 volunteers in 45 countries to enhance the dissemination of research in economics. The heart of the project is a decentralized database of working papers, journal articles and software components. All RePEc material is freely available.
NNMATH a project in progress to create an open access database of reviews of mathematical articles.
Wikipedia: not necessarily written by academic authors
Interdisciplinary Documentation on Religion and Science: "a natural expansion of the work carried out preparing the Dizionario Interdisciplinare di Scienza e Fede, published in Italian in 2002 (Rome: Urbaniana University Press - Citta Nuova, 2002), partly translated into English and offered here on-line."
Peter Suber's list of OA-related conferences and workshops
Peter Suber's timeline of the OA movement
Peter Suber's list of what you can do to promote open access
An Open Letter to the U.S. Congress Signed by 25 Nobel Prize Winners (August 26, 2004) in support of a bill requiring all research funded by the National Institutes of Health to be published in an open access form