Maggie Sensei is a Japanese grammar guide site designed to teach Japanese as it is used in everyday life. The site's mascot is a dog named Maggie (who, sadly, has passed away). Lessons are brief and provide easy-to-understand explanations of various grammar points. And there are a lot of lessons. They are categorized using a number of handy tags such as, "JLPT N3" and "Formal Japanese" and "Emergency."
Maggie Sensei does a great job of explaining the various usages of grammar points and providing loads of example sentences to drive home each possible situation. Because Maggie Sensei covers so many different grammar patterns, if you couldn't find information about a particular grammar usage elsewhere, Maggie Sensei might be the place to go.
The site uses pictures of readers' pets and turns them into comics that demonstrate the grammar point in question. The site’s style is very kawaii, but it lacks formatting that would make reading articles a little easier. All examples are written three times: first as you would write it in Japanese normally, second in romaji, and third with the English translation. The site puts out articles regularly, and has been doing so since 2008.
Articles are not organized in any particular order; you will have to search for a specific grammar pattern if you would like to find out what Maggie says about it. Unlike Tae Kim's guide to Japanese, Maggie Sensei's website is set up less like a textbook and more like a blog.