writing

• Google IME - software to type in Japanese
• How does kanji stroke order work?
• Nihongoresources: Japanese Type Faces
• How to Write Letters in Japanese

reading

• Rikaichan for Firefox / Rikaikun for Chrome - browser extensions that shows dictionary definitions when hovering over Japanese words
• Capture2Text - converts images and audio to clipboard text
• Kanji Converter - convert between kanji, kana, and romaji
• Handwritten kanji search

dictionaries

• Denshi Jisho - online Japanese dictionary - searchable in Japanese or English, searchable by kanji radical, has a ton of info like stroke order and example sentences
• Nihongoresources: Kanji Dictionary
• Yamasa Institute Online Kanji Dictionary
• Kanji Damage - kanji dictionary and guide, ordered based on radicals (warning: I haven’t explored the whole site but I’ve seen the r-slur crop up multiple times)
• Nihongoresources: Names and Places Dictionary
• The Jaded Network: SFX - onomatopoeia dictionary
• Nihongoresources: Onomatopoeia Dictionary
• Japanese Idioms
• RNN - current affairs dictionary
• The Japanese Slang Jiko

databases and guides

• Tae Kim’s Guide to Learning Japanese
• Japanese Guides and How-Tos
• FAQ about Japanese
• JGram - online grammar database
• Nihongoresources: Grammar - free online textbook
• Nihongoresources: Particles
• Learn Japanese articles on Tofugu
• Useful Notes: Japanese Language
• Japanese on About.com
• Japanese on English Wikipedia

studying

• Tagaini Jisho - kanji flashcard software
• Japanese Language Proficiency Test Resources
• Lang-8 - site for writing journals in any language and getting feedback from fluent speakers

last resort

• Google Translate