Chris Witcomb's Art History Resources - don't be fooled by the cheesy splash page: There are some good links here!
ARLIS/NA Free Art Resources on the Web - maintained by the Art Libraries Society of North America
New Pauly Online - The classical scholarly world's encyclopedia. Signed articles (ie, you can quote them in your papers), reliable data, core bibliography.
don't forget THE SECRET WEAPON PQDT (Dissertations full-text) - 90% full text, super scholarly, keyword searchable, unique primary sources often in the back as appendices (more here)
L'Annee Philologique - the standard index for the ancient world. All civilizations and topics.
- TIPS: Advanced Search -► under THEMATIC SEARCH ► click "More Search Possibilities" ► next to "All Index Fields" type in Greek (or whatever area).