ATLA: American Theological Library Association
ATLA is supported by EBSCOhost (epnet.com)- world's premium research database service. It serves thousands of libraries and other institutions with premium content in many subject areas. Includes journal, book and article search capability. Very comprehensive.
A keyword approach to searching 7 different versions of the bible.
BUBL Link Catalogue of Internet Resources. Very comprehensive gateway covering many subject areas.
Separate pages on Christianity, Islam, and Judaism are listed in BUBL.
Comparative Religion: A Directory of Internet Resources for the Academic Study of Religion
A massive site with all manner of information from bibliographies, concordances, dictionaries, texts and links to hundreds of other sites on all religions. It lists several Internet guides to religion.
intute: Religion and Theology
Religion web resources reviewed and evaluated by subject specialists.
Religion on the Web
The easy to use index provides ample access to non-Christian religions as well as links to the author's sections on Philosophy of Religion, Individual Philosophers and Scepticism for the non-believer.
Religion Web Sites
Multi-faith sites, encyclopedia, concordances, dictionaries and databases.
Voice of the Shuttle: Religion
As ever the VoS web site is very comprehensive. Depending on your field of interest you may also wish to look at the VoS sections on History and Classical Studies. Simply click on the VoS home page icon to get a list of all the main sections.