This is a comprehensive list of resources for learning Japanese.
100 Best Resources For Learning Japanese
This list provides a range of resources to help you learn Japaense.
Rikaichan is an add-on for Firefox. After you install it, you’ll be able to activate it, and then everything Japanese you hover your mouse over will come up with a bigger version of the kanji (if there is one), the hiragana, and then the English translation for it.
An online Japanese Dictionary that allows you to search for Kanji by radical.
jGram is a database of Japanese grammar.
This is as close as you’ll get to finding a free online Japanese textbook.
Kids web Japan
Lang-8 Multilingual website