Freeplane - Freeplane is a powerful and free software for building mind maps.
Machine Learning Flashcards - 300 digital flashcards
vym - VYM (View Your Mind) is a tool to generate and manipulate maps which show your thoughts.
The Examiners - Quiz & flashcard generator for bioscience & medical students
SuperNotecard - Introducing SuperNotecard. SuperNotecard is an online writing tool that features virtual notecards to help arrange facts or scenes, track details, organize paragraphs, and clarify your composition process.
Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.