Spaced repetition, Anki-style flash cards. Do they work because they present to you the information you're just starting to forget in just the right moment? Or maybe their success is (also?) due to placing you in the stressful situation of trying to recall in a competition-like setting? Contrast spaced repetition flash cards that just repeat data to you vs. those that ask you to recall with a question/answer format. If the hypothesis is correct, the latter will be much more successful.

Active elicitation and testing does work better than mere exposure; see http://www.gwern.net/Spaced%20repetition#background-testing-works and also search for 'feedback'.