A useful source for additional Athenaze exercises, vocabulary drills, and grammar review.
A useful collection of Latin review exercises on the grammar and vocabulary in Wheelock's Latin.
A site with a collection of fun and useful Latin sayings for everyday (and not so everyday) situations.
A site sponsored by Cornell University which offers a review of Greek and several beginning and intermediate Greek texts from the New Testament and Plato to practice your skills. These are especially useful to practice during the summer.
An online Greek and Latin lexicon that allows one to search for any word you do not know in an ancient text (or homework assignment).
A nice link to an organization that offers additional language help, free posters, links to cool Greek and Latin t-shirts, and various other information that will help excite you about classical languages.