Open Access

Open Access (OA) literature is digital, online, free of charge, and free of most copyright and licensing restrictions. What makes it possible is the internet and the consent of the author or copyright-holder.

-- from A Very Brief Introduction to Open Access by Peter Suber

Open Access Factsheets

Open Access Resources

• Open Access - CARL (Canadian Association of Research Libraries)
• Open Access - SPARC (Association of Research Libraries)
• Peter Suber's Guide to Open Access
• Wikipedia Entry for "Open Access" 
• OATP Primary (remixed feed)

Resources for Authors

• Resources for Authors - CARL
• SPARC Canadian Author Addendum
• Resources for Authors - SPARC
• SHERPA/RoMEO
• What Faculty can do to promote Open Access

As in any business there are quality Open Access publishers and those with questionable motives and/or quality. Some sources to consider:

Open Access Journals

• DOAJ (Directory of Open Access Journals)

Open Access Textbooks / Books

• Athabasca University Press
• Bookboon (free OA textbooks)
• Directory of Open Access Books
• OAPEN (Open Access Publishing in European Networks) 
• Open Access Textbook Project  
• Open Humanities Press 
• Open Stax College (Rice University) 
• University of Minnesota Open Text book Catalog 
• University of Saskatchewan Open Books links

Open Courseware

• Harvard Open Learning 
• MIT Open Courseware
• Open Courseware Consortium

Open Access Repositories

• BASE (Bielefeld Academic Search Engine)
• OpenDOAR (Directory of Open Access Repositories)
• ROAR (Registry of Open Access Repositories)

Open Access Theses

• Theses Canada - Library and Archives Canada
• Networked Digital Library of Theses and Dissertations

Other

• Academia.edu
• Internet Archive (includes texts, audio, video) [Everything is Open Access]
• Coursera (Open University Courses)  [Courses are open, educational materials are not]
• EdX (Harvard, MIT, Berkeley) [Courses are open, some educational materials are open]
• F1000Research [Biology and medicine open repository of posters and slideshows]
• HippoCampus [collection of education multimedia content hosted by the Monterey Institute for Technology and Education].
• Udacity [Courses are open, educational resources are propriatorial]

This is not an exhaustive list.  Always check the copyright and permissions conditions before using material from any of the sites.