Spaced Repetition
A system to help facilitate rote memorization.
One of the most popular Spaced Repetition Systems (SRS) is Anki.
Anki is a great way to transfer the content that you are studying into long term memory. I should point out that this should only be necessary in a few situations. It's much more efficient to be able to reference something rather than memorizing it. However, you may want to commit something fully to memory (e.g. learning Kanji
The basic concept is that if you're familiar with something, you will see that card less frequently. The things you aren't familiar will show up more often. It's required of you to judge yourself honestly (i.e. you will be in control of deciding how well you know something).
Custom SRS
I built a custom SRS for learning hiragana and katakana
This is basically digital flash cards.
Custom vs Anki
I would Anki is great if you're really trying to commit something to long term memory. It has systems that will space cards that you're comfortable with over several days and sometimes weeks.
A custom solution would be better if you're just trying to capture the basic concepts of something that you can then reference later. It might also be good for learning something that isn't extremely dense. With the custom solution, I was able to learn (read not write) hiragana fairly well in less than a week.