DreamKana is a freeware hiragana and katakana flash card application. It is easy to use and flexible to the way you want to learn. It includes voiced constanants in both kana sets, and does not require special fonts or language packs.
Watch the popular Matrix Screensaver in Kryptile Design style! Matrix glyphs include reversed letters, numbers, and Japanese katakana characters. The Matrix code flows down the screen leaving a greenish trace, just as in the movie!