There's a great cumulative meme going around: name five early (pre-1800) women writers. The list so far is at Bardiac.
(1) Damaris Cudworth (Lady Masham) -- Occasional Thoughts
(2) Catharine Trotter Cockburn -- The Defence of Mr. Locke's Essay of Human Understanding
(3) Anne Finche (Viscountess Conway) -- The Principles of the Most Ancient and Modern Philosophy
(4) Hester Thrale (a.k.a., Hester Lynch, Hester Piozzi) -- Anecdotes of the Late Samuel Johnson
(5) Sor Juana Ines de la Cruz -- Reply to Sor Philothea
I'm fairly sure that none of these have been mentioned yet by anybody, although it's difficult to be sure. If some of them have, I'll have to enlist Catherine of Siena as my back-up writer.