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.

Cram - Cram is an app for Android, Windows and Apple devices that allows you to search for flashcards in a range of topics to study for an upcoming test or to learn new information. Read more about Cram.

Repetitions - Repetitions is a cross-platform spaced repetition system (SRS), an intelligent flashcard application that makes learning and memorization easy.

RemNote - All-in-One Tool For Thinking & Learning

LearnObit - A tool for your learning, like Anki & Workflowy in one

The Mnemosyne Project - Mnemosyne (named for the Greek goddess of memory, Mnemosyne) is spaced repetition software...