Oracle Official Documentation site

Oracle Administration

Oracle development

Oracle Security

Oracle Tuning related Sites

Oracle Tuning related Articles

Oracle related blogs (in non particular order):

Catherine Devlin, Catherine: pyOraGeek
Jonathan Lewis, Oracle Scratchpad
Tom Kyte, The Tom Kyte Blog
Doug Burns, Doug’s Oracle Blog
Fairlie Rego, el-caro
Kevin Closson, Kevin Closson’s Oracle Blog: Platform, Storage & Clustering Topics Related to Oracle Databases
Connor McDonald,
Mogens Norgaard, We Do Not Use Blogs
Niall Litchfield,
Tim Hall, The Oracle-Base
Nuno Souto (noons), DBAs-R-Us
Mark Rittman, Rittman Mead Consulting
David Aldridge, The Oracle Sponge
Jeff Hunter, So What Co-operative
Pete Finnigan
William Robertson, Oracle WTF
Laurent Schneider
Chris Foot,
Pythian Group
Scott Spendolini
Sue Harper, Sue’s Blog… again…
Andy Campbell, Oracle Stuff I Should Have Known
Eddie Awad
Daniel Fink, OptimalDBA
Inside the Oracle Optimizer – Removing the black magic
Cary Millsap
ASH Masters
Alberto Dell’era
Tanel Poder
Miladin Modrakovic
Howard J. Rogers blog