The domain suffix of a website (the postscript at the end of a web address) can be a good indicator of the the website's authority and accuracy.
Pew Research Center: Religion & Public Life
Contains current research and analysis focused on religion and how it impacts issues in public life and trends in the world.
A government resource that provides facts from a variety of areas in the US government.
Features materials on 20 of the world's most popular religions
Harvard University's Pluralism Project
Extensive research project undertaken by Harvard University that studies the religious diversity of the United States
A digital index of concepts, names, events, etc. associated with individual religious backgrounds and belief systems.
Largest freely available archive of online materials on religion, mythology, folklore and the esoteric.
Library of Congress - the largest research library in the world
the ARDA - The Association of Religion Data Archives
The NTSLibrary - Online Christian Library
Jewish Virtual Library - coverage of Jewish and Israeli history
The Buddhist Society - Information resource for Buddhism research and practice
Religion Online - educational resource for exploring religious issues
Digital Vatican Library - the Vatican's digitized manuscript library
Islamic Library - free online library of Islamic books
World Religions & Spirituality Project - Comprehensive coverage of the world's religions and spiritual groups
Wabash Center - Websites and other materials on religion and theology