When it comes to learning Japanese, I haven't heard many good things about audio-based methods like Rosetta and Pimsleur. I don't really know any Japanese-language learning community that takes Rosetta Stone very seriously.
Here are some of the best resources I've come across:
Review
Anki - pretty much
the app for learning Japanese, along with a lot of other things. It doesn't come with any content. Anki is just an app for "intelligent" flashcards that use SRS (spaced repetition system) so that cards come up for review at the times most efficient for retention. Lots of online resources rely on Anki for review, and provide "decks" than can be used with it. There are desktop, iOS, and Android apps. Although great, Anki is a bit "bare-bones" compared to the more polished built-in review applications some sites provide.
Kanji
Remembering the Kanji - probably the seminal book on learning Kanji by Heisig, based on "primitives", many of which are based on the radicals that make up kanji. The Heisig method is based on using the primitives to create mnemonic stories to remember the meaning of the kanji. Exists in book form. The website is only a forum for the book. The first book doesn't teach any readings, only meanings or "key-words". Later volumes teach readings, too.
WaniKani - a part of the TextFugu family, focusing on teaching kanji and vocabulary. The method is Heisig-based, using radicals as building blocks. Like Heisig, many of its "radicals" are made up, where some are based on the radicals used by Japanese linguists, and many are made up for convenience of learning. It is a paid site, currently in beta, that uses SRS and is very nice to use. Teaches both meanings and readings, and a lot of vocab.
Kanjidamage - another site that uses the Heisig method, but again with its own system of made-up radicals. This site is free, but I find its radicals and the mnemonics are a
bit lot more juvenile than Heisig or Wanikani, which can be a bit of a turn-off or a point of attraction for some people. The website only gives the order for learning and kanji information, but there are a lot of community-made Anki decks for Kanjidamage.
Grammar
Tae Kim - Like Heisig, Tae Kim is probably the seminal online guide for learning Japanese grammar. It's free, and has a lot of great material. Very nice site, and there is also an iOS app. Although it also has a lot of great tips when it comes to what's "natural" vs what's "correct", it doesn't always go into enough detail to be completely thorough.
Imabi - An extremely thorough grammar guide with almost 300 lessons. Imabi is much more in-depth than Tae Kim, so can be a very daunting to the beginner. This is probably the way to go when you get to intermediate/advanced, because the author goes to great extents to get things right. Lots of examples, and the author is happy to help anyone who asks questions there.
Textfugu - A very beginner-friendly online textbook by the same people as WaniKani. It's a paid site, but I think it's a nice and gentle introduction that still doesn't pull any punches (e.g., getting romaji out of the way as soon as possible). A better walkthrough than Tae Kim or Imabi, but not nearly as useful as reference material. It is due for a major content update soon.
Lang-8 - Not actually a grammar-learning resource at all, but a website to practice it. The idea behind the site is you make posts in the language you want to learn, and native speakers correct your posts. (You'll be expected to correct posts by other users who are learning your own native language, too.) Very useful for practice. Sometimes the corrections aren't the most helpful if you can't understand the reasons for them.
Vocab
iKnow - A paid site that provides its own online SRS interface (also available in iOS app). Its lesson and review interface is very nice, and mixes up the audio vs text and also recall vs recognition. Its various "Core" courses teach the most-used vocab. These "Core" courses are also widely used by the community as unofficial Anki decks. (The Anki decks are a bit outdated, from when the order was based on newspapers, so lots of less-useful political words are presented earlier than they are on the site, which has since revised the order.)
Memrise - A free site that also has its own SRS. Lots of people like it because you get to "choose" your own mnemonic from various user-created ones, but it's a little less polished than a paid site like iKnow. It's a great site overall, but I think it suffers a little from not being a Japanese-focused site like most of the others mentioned above.