There's actually an open source app which functions similarly to super-memo, but uses an older spaced repetition algorithm and doesn't quite have the same feature set. Its called Anki (http://www.ankisrs.net), and its been a godsend for both myself and many friends who learn Japanese.

The thing I found interesting in this article is that switching contexts actually increases the amount you can learn. From what I understand, this would mean studying grammar, character reading/production and vocabulary at the same time would be beneficial. I never quite understood why this was the case before, even though people have told me it is so.