StudySmarter - Your lecture notes, flashcards, summaries, learning with friends, statistics, and even rewards for learning - all in one place and just a click away - StudySmarter.
Kanji Book - Learn Japanese online with kanji mnemonics. Study all of the jōyō kanji with the best spaced repetition system. It's easier and better than any flashcard app.
Anki - Anki is a program which makes remembering things easy. Because it's a lot more efficient than traditional study methods, you can either greatly decrease your time spent studying, or greatly increase the amount you learn.
VocApp.com - A clever way to expand your vocabulary will allow you to take you to a higher level of language.
LaTeX Cards - The mobile app to create cards to learn your formulas and theorems using LaTeX.
iGNUit - iGNUit is a memorization aid based on the Leitner flashcard system.