QuizUp - QuizUp gives you the opportunity to test your trivia skills against friends and strangers throughout the world.
Tweeticide - Tweeticide – Delete All Tweets is a commercial app that enables you to delete all of your tweets at once.
A Google a Day - Online trivia game where you use Google's search to answer questions as fast as you can.
Wali - Share and create watchlists
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
Tweedle App - Notion is nice but sometimes all you need is an app like Tweedle.