Backstory: I find the business model of Blinkist very intriguing. For those of you who aren't familiar with the service, Blinkist summarizes popular business books into 5-10 minute reads so that you don't have to read the whole thing. They even have audio versions for some books. I like this business model because they don't have to think all day about what they are going to write about, they just pick the top books related to business.
The Idea: Summary of all your favorite content across all mediums.
Deep Dive: Take the best content in a specific niche, condense it, and then sell that content. Here are examples of niches that could be summarized:
Similar to Blinkist, this service could charge a monthly subscription for access to all of the content.
Validation: Blinkist exists and this would be across different pieces of content.
Monetization: You would charge a monthly fee for the service. You could offer a freemium plan that only links a few types of media.