'Open access' means freely available. There is a wealth of information now published online that is freely available, including peer-reviewed academic journals. The following is a list of some databases sorted into subject areas.
For more databases by subject see Libguides - subject guides
Australian Bureau of Statistics
Directory of Open Access Journals (DOAJ)
Google Scholar
Highwire Press (Stanford University)
Resource Library - CBS Interactive Business Network
Trove - National Library of Australia
WorldCat
ERIC - Education Resources Information Center
IDP Database of Research on International Education
MERLOT - Multimedia Educational Resource for Learning and Online Teaching
VOCED - tertiary education research database - NCVER
AGRICOLA - US National Agricultural Library
PLoS - Public Library of Science
BioMed Central
Cochrane Library
Free Medical Journals
HealthInsite
Medscape Reference
PubMed Central
Austlii - Australian Legal Information Institute
ComLaw
Victorian Legislation and Parliamentary Documents
Google Books
Project Gutenberg