Aeschylus himself appears as a character in a play by another ancient Greek playwright named Aristophanes. The title of the play? The Frogs. What's a serious dude like Aeschylus doing in a play with a title like that? Actually, Aristophanes's play is a comedy. The story takes place right after the death of Euripides, a hell-raising playwright who was born about 40 years after Aeschylus. In the play, the god Dionysus goes down to the underworld to bring Euripides back. Along the way, he passes the river Styx, which is swarming with frogs chanting "Brekekekek koax koax." At the end of the play, Euripides goes head to head with Aeschylus in an underworld poetry slam. Want to know who wins? You can read the play here to find out.
Aeschylus's Oresteia (of which the Agamemnon is Part 1) is the only surviving ancient Greek tragic trilogy. Many people think that the Oedipus plays of Sophocles (Oedipus the King, Antigone, and Oedipus at Colonus) are a trilogy, but these plays actually come from different trilogies and just happen to all connect in some way with the story of Oedipus. So, these plays by Aeschylus provide a very important window into this ancient art form. (Source)
The great nineteenth-century English poet Robert Browning produced a complete translation of Aeschylus's Agamemnon in verse. You can read it here.
The Irish poet William Butler Yeats wrote a poem about how the god Zeus took the form of a swan to seduce the mortal woman Leda. As a result, she gave birth to Helen and Clytemnestra – two ladies who ended up being bad news to Agamemnon. Yeats alludes to this future history in his poem, which you can read here. While you're at it, why don't you check out Shmoop's analysis of Yeats's poem here.
The Nobel Prize winning Irish poet Seamus Heaney wrote a poem based on Aeschylus's Oresteia, entitled "Mycenae Lookout." Some critics have interpreted this poem as a veiled reflection on the violence in Northern Ireland. You can read the poem here. Be forewarned though: this poem contains language that some may find offensive.