QuickMem Greek
A program to test you on your New Testament Greek vocabulary can be freely downloaded, although you are asked to register on a voluntary basis. These vocabulary flashcards are grouped in 35 lists, according to their frequency in the New Testament and based on B.M. Metzger's, Lexical Aids for Students of New Testament Greek. Since these are same lists for our vocabulary quizzes, this should be very useful! 

The Liddell - Scott Lexicon
The standard lexicon for non-biblical Greek literature

The Perseus Project morphology analysis
If you really need help with a form, this may aid you in identifying the form of the word.

Grammar of Septuagint Greek
Written by F.C. Conybeare in 1905.

Syntax of the Moods and Tenses of the Greek Verb
William W. Goodwin's  book from 1889, focusing on classical Attic Greek.

Syntax of the Moods and Tenses in New Testament Greek
Ernest de Witt Burton's 1898 book is still useful. 

A Greek Grammar for Colleges
Herbert Weir Smyth's grammar has been a standard reference for classical Greek.

Interpreting Ancient Texts
A very useful site which explains the practice and history of textual criticism, and the various reasons for variant readings. It also includes images of several manuscripts and a fun English exercise in textual criticism.

Duke Papyrus Archive
A great collection of images of papyrus documents.

University of Michigan Papyrus collection
A searchable set of images from one of the world's largest papyrus collection, with images of the papyri and translations.

Ancient Inscriptions
Just in case you get hooked on trying to decipher those inscriptions, here are some photos of ancient Mediterranean inscriptions, grouped geographically, from the Center for the study of Ancient Documents at Oxford University.