This Wired article is fascinating look at the founder of SuperMemo, one of the big players in that industry: http://www.wired.com/medtech/health/magazine/16-05/ff_woznia... Highly recommended, it's a great read.
http://en.wikipedia.org/wiki/Spaced_repetition_system
they have software where you can set up a flashcard system if you know what you are doing, and it will time out when you should review what for optimal memorization
http://en.wikipedia.org/wiki/Spaced_repetition