That's a good suggestion, Mikawa. Actually there was one aimed at kids, "Kakitori-Kun" which I think just covered the 教育漢字 or some amount around that. Another 'competitor' in the Japanese language market would be
these folks, who I remember have nice content but at least on the web version their interface is very clunky.
[MENTION=4386]saren[/MENTION] - it does look like you have the technical skills to pull off something really nice. I just would like to see someone in the English-language market do something which isn't just kanji flashcards, filled up with the same old info from kanjidic.
For example, in the kanji game I most enjoy fiddling around with, "Nazotte Oboeru", they have theme quizzes, getting enough right opens up new quizzes. Some of these quiz questions form little stories, others are just on a theme (names of sports, for example). In the Kanken DS series there's usually some sort of timed game where you have to read what kanji word is written on the side of a car before it drives away, or something similar.
The power of these programs imo is:
1) They quiz you on things that you need to actually read/write Japanese. Recognising how to read and write 正しい and 正直 is vastly more useful than just remembering "ただ-" and "ショウ"
2) Input of answers is always via handwriting recognition, no multiple choice.