Mnemosyne (official website) is spaced repetition flashcard software, similar to SuperMemo (official website), the dominant memory software.
Basically, you can think of Mnemosyne as a kind of flashcard system. The difference between it and traditional flashcards is that when you review a flashcard, you give it a grade from 0-5. Depending on how you grade the card, the program decides when it will show you the card again.
In other words, you review your cards once when you want to learn them, and after that the program decides when you should review. As you give the program more grades, it gets a better idea of when to schedule the cards.
Using SuperMemo-- software much like Mnemosyne-- I managed to pass the 2kyuu after four months of study. (I had, however, studied Japanese on and off for three years prior to that point.)
But, Mnemosyne has several advantages over SuperMemo:
Mnemosyne will only help you speak Japanese indirectly, but it can improve your reading and comprehension ability dramatically if you use it every day.