Math Girls is Hiroshi Yuki's immensely popular series of fiction and manga about math geeks ("Like Glee for math nerds"), and the stories themselves are a potted education in all sorts of mathematics. The first volume of Math Girls is to be published in English shortly by Bento Books, and they've posted a brief excerpt in PDF form. The site is short on actual details (publication date, ISBN, etc), but I'm looking forward to the book becoming reality nevertheless.
(Thanks, Sohagan!)