Some online books on Aeschylus' Agamemnon I've found after a quick search: please add others if you find them - will be helpful for the reading group!
You can only post 10 links per post, so here's part 1:
Comments on the play
Peile:
http://archive.org/stream/agamemnonaesc ... 0/mode/2up
Headlam & Pearson:
http://archive.org/stream/agamem00nonof ... 6/mode/2up
Raeburn & Thomas (google books preview only, won't fully display all pages):
http://books.google.fr/books?id=8lFoLIY ... &q&f=false
Sidgwick:
http://archive.org/stream/aeschylusagam ... 2/mode/2up
Conington footnotes:
http://archive.org/stream/agamemnonaesc ... 2/mode/2up
Adler:
http://archive.org/stream/notesoncertai ... 8/mode/2up
Felton:
http://archive.org/stream/ag00amemnonof ... 2/mode/2up
Kennedy footnotes:
http://archive.org/stream/agamemnonaesc ... 4/mode/2up
Paley:
http://archive.org/stream/agamemnonaesc ... 0/mode/2up
Verrall:
http://archive.org/stream/agamemnonofae ... 1/mode/2up