Visual Beat - Interactive music video
myQuiz.org - myQuiz is an Audience Engagement Cloud Platform
The Lucid Realm - Listen to music in 3D
TestMOZ - TestMOZ is an online platform for creating interactive quizzes and questions to keep your audience engaged on your social media, websites, or blog channels.
Google Music Lab - Interactive experiments that use the Web Audio API
QuizWhizzer - QuizWhizzer is a platform that allows you to create a quiz to engage your audience inactivity.