QuizUp - QuizUp gives you the opportunity to test your trivia skills against friends and strangers throughout the world.
Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.
A Google a Day - Online trivia game where you use Google's search to answer questions as fast as you can.
Standard Notes - A safe place for your notes, thoughts, and life's work
Trivia Crack Kingdoms - The amazing quiz game that lets you test your knowledge and challenge your friends to see who is the smartest. Developed by Etermax
Joplin - Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, tagged and modified either from the applications directly or from your own text editor.