Oxford graduate student, Andrew Stiles maintains this portal to the most important classics-related web resources available. To successfully link to some resources in the list such as TLG and L'Anneé Philologique, access them via the Research Databases list on the library website.
Index of Biblical Quotations and Allusions in Early Christian Literature, being the contents of the printed Biblical Patristica. "This site already allows simple interrogation in a corpus of about 400,000 biblical references."
This used to be a free resource but now requires a subscription. I left it on the list to make folks aware of it, and perhaps the library will subscribe if there's demand. Based on the printed version of the 14 vol. German work by the same name, this site is being constantly updated, and the editors accept suggestions for entries. To be included the person must be dead.
The New Testament Gateway is a comprehensive directory of academic internet resources related to the New Testament. It is divided into several sub-directories and dozens of pages, each relating to a specific topic. Every link is annotated. The annotations help users to pinpoint the information for which they are looking.
The Theological Commons is a digital initiative of the Princeton Theological Seminary Library. Begun in 2011, its purpose is to improve access to the digital and non-digital material held in the Library and, in particular, to bring Princeton Seminary’s digital collections together in a single more convenient framework, making searching and viewing of those collections easier and quicker.