New Testament Gateway (http://ntgateway.com) - excellent portal for New Testament Studies and related fields.
Resource Pages for Biblical Studies (http://torreys.org/bible/) - contains int. al. links to sources about the social world of the ancient Mediterranean.
Rutgers University Virtual Religion Index (http://virtualreligion.net/vri/) - offers a large collection of links to Internet sources on religious topics, including Ancient Near Eastern, Greek and Roman religions, as well as the Hebrew Bible and the New Testament.
ABZU (http://www.etana.org/abzubib) - contains a large collection of sources (including the complete texts of books) on the Ancient Near East.
Ancient Near East.Net (http://www.ancientneareast.net) - contains a collection of sources and links on the ANE for researchers and laypersons. [ACCOUNT SUSPENDED]
There are several websites with bibliographical information about specific ancient authors.
The more general sources are the following:
L'Année philologique (http://www.annee-philologique.com/) - an Internet version of the most important bibliographical aid for Classical Studies. Admission is only by subscription, but it is free through the Stellenbosch University Library's website (http://www.sun.ac.za/library). Follow the link to Databases and choose L'Année philologique (alphabetised under A).
American Schools of Oriental Research Publications (http://www.asor.org/pubs/index.html) - with links to the journals Bulletin of the American Schools of Oriental Research, Journal of Cuneiform Studies and Near Eastern Archaeology.
Brynn Mawr Classical Review (http://bmcr.brynmawr.edu/) - reviews of books on Classics. One may search the website or subscribe to receive reviews by e-mail.