Pop music might come off as formulaic sometimes, and, to some extent, that's probably true. Hook Theory is a song database, and after analyzing 1,300 popular songs, looking at the chord progressions in each, it spit back some pretty cool visualizations.

It's a lot of fun to look at, and there's a blog post you can read about the statistics uncovered from it, but the most interesting part is probably that it can predict what chord will come next in a song.

For example: If you're playing in the key of F and move to an A minor chord from an F major, popular songs are 67 percent likely to follow it up with a D minor chord. The Beatles' "A Day In The Life" follows that progression; so does "Float On" by Modest Mouse.