Theoi Greek Mythology - The THEOI Project web site is a comprehensive collection of encyclopedia articles, maps, galleries, and guides for learning about Greek mythology. In particular, this site focuses on ancient Greek gods, spirits, and monsters.
Bulfinch's Mythology - Popular translation of Greek myths.
Classical Mythology - Begin with the table of contents within the "About the Book" link. If you see a chapter that interests you select "Student Resources" ----> "Chapter Materials" from the menu on the left.
MythWeb - Stories about the heroes, gods, and monsters of Greek mythology.
Greek Mythology Link - Comprehensive guide to myths of Greece, containing sections on major events in Greek mythology; individual entries for divine, mortal, and semi-divine characters; genealogical tables; maps; a bibliography of ancient and modern sources; and an extensive set of links to sites of Classical interest.
Greek Gods and Religious Practices - Metropolitan Museum of Art
Timeless Myths - Begin with the "Classical Mythology" link
The Immortals - a list
The Greeks - PBS companion website
The Greeks - at History for Kids
Hercules - Greece's Greatest Hero
Ancient Greece - from the BBC
Ancient Olympic Games - from Penn Museum