Yeah, I know--referring to wikipedia is getting to the point where it's almost equivalent to handing someone a dictionary.
And yet, you know: if one is wondering about any particular sub-branch or just plain where to get started, Wiki's feminism section isn't bad. Especially once you start surfing the links within.
Clarify the difference between post-feminism and postmodern feminism. Use their list to track down anyone from Sor Juana to Ana Castillo. Learn a brief history of birth control (mmm, crocodile dung and catgut condoms); and why Margaret Sanger remains controversial; and where, in fact, the term "Ms." originated...or, for that matter, the term feminism.
"And much much more!"
Anyway, happy exploring.