Tae Kim's Japanese Grammar Guide -
I am putting this together as I go through the book, so it is incomplete for now...
In addition to the below, you'll also want an IME installed to type in hirigana/katakana/kanji.
JPLTBootcamp talked about that here -
Welcome to Memrise!
Join millions of people who are already learning for free on Memrise! It’s fast, it’s fun and it’s mind-bogglingly effective.