FlipToMind - Space repetition app to help you remember everything
Mochi - Write notes and flashcards with Markdown and study them with spaced repetition.
Memory Health Test - Track your memory performance with a fun online test
Yak Tack - remember. words.
Deal of Fortune - Your favorite game show combined with a memory game.
Zorbi - Spaced-Repetition Flashcards - Other tools are built by boomers, Zorbi is built by students.