Let's Learn Japanese Language (q,r,s,t).

a. http://www.language.tiu.ac.jp/
b. http://www.popjisyo.com/
c. http://www.fll.purdue.edu./ultimateKatakana.htm
d. http://www.csus.edu/indiv/s/sheaa/projects/genki/katakana-timer.html
e. http://www.learn-hiragana-katakana.com

Any comments ?