Although it has existed since 2003, BookBlog's Gender Genie was news to me. Based on the research of Moshe Koppel, Bar-Ilan University in Israel, and Shlomo Argamon, Illinois Institute of Technology, the Gender Genie implements an algorithm that (sometimes) predicts the sex of the author of a piece of text.
I must say, this premise seemed odd to me. I don't tend to assume that there is some algorithmically determinable masculinity or femininity to any text, but of course, the first thing I tried was... READ ON