Perseus. Start here for most searches for texts, translations, maps, images, etc. of the Greek world (it can also be helpful for Roman things as well).
Stoa is a consortium for online publication that links to a number of valuable sites, for instance: Suda-On-Line, Ancient City of Athens, Demos (on the workings of democracy in classical Athens); Metis (QTVR panoramas of Greek archaeological sites and monuments); go here also to find a number of classical blogs.
Rassegna degli Strumenti Informatici per lo Studio dell'Antichita Classica is another source for digital resources on the classical world.
Greek and Roman Texts
Thesaurus Linguae Graecae, also available as a database through the SCU library, contains digitalized Greek texts from Homer to 1453 C.E.
The Internet Classics Archive provides English translations of 441 texts (most but not entirely Greek and Roman).
Latin Inscriptions-The Internet Release provides a link to over 100,000 texts from L'Année Épigraphique, C.I.L., and Dessau's Inscriptiones Latinae Selectae.
Finding Your Way Around Ancient Greece and Rome
Ancient World Mapping Center promotes cartography, historical geography, and geographic information; use this site for digital maps.
Maecenas: Images of Ancient Greece and Rome is just what is promises.
The Princeton Encyclopedia of Classical Sites, found within Perseus, is supplemented by The Perseus Site Catalogue.
Athenian Agora Excavations provides up-to-date information on the excavations with maps, diagrams, QTVR virtual reality movies, and links to other relevant sites.
Ancient City of Athens offers images with essays and links to information about Athens.
VRoma provides online resources for learning about the Latin language and ancient Roman culture with images, texts, translations, articles—and it will even speak with you in Latin!
The Rome Project offers an excellent collection of resources for the study of classical Rome.
Resources on Ancient Greek Myth offers many links to other sites–very helpful for mythology students. See also Resources on Ancient Greek Religion.
Diotima is the most helpful site for women, gender and sexuality in ancient Greece and Rome
Classics Podcasts available from Haverford College.
Bibliographies of Classical Scholarship
L'Annee philologique, an index to work published since 1924 in fields related to the language, literature, history, and culture of ancient Greece and Rome, is the standard bibliographical tool for research in Classics. The online electronic version covers the years 1949-2005. It is available as an electronic database through the SCU library.
Gnomon on-line is a good place to start to find recent books and journal articles in Classics.
Bryn Mawr Classical Review publishes online reviews (often review essays) of recent books in all areas of Classics.
The On-Line Survey of Audio-Visual Resources for Classics is useful in finding movies and documentaries produced about a wide variety of classical topics.