Japanese Lesson

Japanese Lesson is a great site for learning the Japanese writing systems. Hiragana, Katakana and Kanji. The site have good explanations and gives you a better understanding of theme.

There are also free digital exercises you can do in order to practice, though I won't recommend it.

I know it's pretty irrelevant but I have to say I love the design of the site:)

Hirgana
Katakana
Kanji