Brainscape is a web and mobile education platform that allows students to study adaptive flashcards.The world's most efficient web & mobile learning platform. Creating a smarter world by simplifying and accelerating the learning process.
That's a fun and intuitive app that every self-organized person from a student to a working professional would really appreciate. I've been using it to prepare for my certification tests as well as to verify my knowledge to keep fit in my professional standing.