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.
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/aph) - 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://library.sun.ac.za//index.htm). 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.