Nihongoresources is an excellent collection of....well, I think the name gives it away. Amongst other things the author (Michiel Kamermans, AI researcher and poet) has created a 285 page grammar guide downloadable as a PDF, a Kansai-ben dictionary, a giongo/mimesis dictionary and an extensive coverage of the Joyo kanji. I enjoyed the description of verb conjugations because of the way Michiel explained the relationship with classical Japanese, making it much easier to see how the language works - so much better than just saying "this is a Group 1 verb and this is Group 2". Great stuff. Hours, nay, days of learning joy. Highly recommended for all levels. Go, read, learn, enjoy.