In response to the women writer's meme (below), and as a reminder that history goes back longer than 300 years, Bardiac posts a challenge (for me, at least): how about including some women writers pre-1800? Great question, especially since I'm really hard-pressed to come up with five whom I can recommend with any knowledge. But I can make some tentative contributions:
Louise Labe, Sonnets (there should be an accent over the e in Labe, but I'm Blogger-ignorant of how to do that)
Sappho. Don't know what a good collection is, though.
Hildegard von Bingen. Again, don't know if there's a collection of her works, but she was a German mystic (I am so ignorant, man, I don't even know what century, but if pressed I'd say 12th).
Susanna Rowson, Charlotte Temple. This one barely makes the pre-1800 cutoff: a novel that explores the dangers of callous British soldiers to impressionable young women.
er... Queen Elizabeth I has that kind of silly poem about her pug dog. Crap, I'm running out of steam here.