JA Sensei - Complete suite to Learn Japanese !
zkanji - zkanji is a free and open-source study tool and dictionary of the Japanese language.
Akebi Japanese Dictionary - Offline Japanese-English kanji dictionary.
Jisho - Powerful and easy-to-use online Japanese-English dictionary with words, kanji and example...
JWPce - JWPce is a free Japanese <--> English dictionary and word processor created by Glenn...
Anki - Anki is a program which makes remembering things easy. Because it's a lot more efficient than traditional study methods, you can either greatly decrease your time spent studying, or greatly increase the amount you learn.