Study Japanese Vocabulary:
http://kanji.asianmideast.duke.edu/
http://www.jlptstudy.net/
www.skritter.com 

Japanese Dictionary:
www.jisho.org
www.japanese.nciku.com 


Japanese Grammar:
http://www.jgram.org/

Listening Practice:
www.japanesepod101.com
http://www3.nhk.or.jp/nhkworld/english/radio/program/index.html