These are some very useful tools that I use to help me learn Japanese and generally keep up with a language that insists on using so many characters. If you are learning I would strongly recommend checking these out. Obviously everyone learns differently but these are top notch.
Anki is the only reason I pass my exams. I kid you not. Anki means ‘memory’ in Japanese. Anki is flashcard software. You create flashcards and Anki tests you on them, remembering whether you got it right or wrong and deciding when you next need to see the card to properly learn it. It is very customisable but it is pretty daunting to start – there are a lot of features and settings to play with. Once you learn the main shortcuts it becomes much easier to handle. It is also both an android and iPhone app as well as a program. I would recommend this to anyone learning a language, or anything that must be learned by rote. Dump the paper flashcards and get ones that can think.
A very simple website for those just starting out in Japanese. This is a way to learn Katakana and Hiragana, the two basic syllabaries of Japanese written language. It will randomly test you on the kana you have selected in a variety of written styles (meaning you can also read handwriting). Not as smart as anki but very effective. It is also an app.
If you are learning Japanese and you have an iPhone you are in luck. Imiwa is only on iPhone as far as I am aware and it is essentially a Japanese dictionary, drawing from many different electronic dictionaries. It also has examples, comprehensive kanji lists of the main school grade level kanji, translations into 4 languages, an ability to create vocabulary lists and a grammar analyser. This is a brilliant tool if you are in Japan and need to know something quickly or if you want to learn the different uses of a word (dictionary definitions are not always very clear). I cannot recommend this enough.
A dictionary program in a similar vein to imi-wa. Not as useful or far reaching but a reliable dictionary with a broad base of vocabulary. Useful when on the laptop rather than on iPhone.
Rikai-kun / Rikai-chan
Indefensible if you are browsing the Japanese web if you are not totally fluent. This is an extension for chrome and firefox. It is a hover-dictionary – if you hover your mouse over a kanji or word it will give you the meaning and breakdown of the word. Very useful when reading the news or an article and you just don’t know all the specialised vocabulary. Rikai-kun is for Chrome, Rikai-chan is for Firefox.
TaeKim’s Guide to Learning Japanese
This is an online grammar guide that provides good starting grammar in Japanese. A good resource to double check grammatical rules and possibly a good resource for self-study. Goes up to fairly advanced expressions but does not cover everything.