Barteleby.com: Aeschylus: Includes brief biography, etexts of the Orestian trilogy and "Prometheus Bound" from the Harvard Classics, and quotations.
Enjoying "The Seven Against Thebes" by Aeschylus: Provides a general overview of contemporary issues and major themes, compiled by Ed Friedlander.
The Suppliants: An introduction to the play by Aeschylus.