Radio Time Machine
Being a great fan of the Billboard Charts myself found this amazing musical time machine app (Click Here), where you can go back in time to hear how popular music has changed from 1940 to today, as told by the Billboard Top 100. To hear full songs, make sure you’re logged in to your Rdio account in this browser. Don’t have an account? Create one, it’s free.
Radio Time Machine taps into the massive music library at Rdio the other Spotify to assemble a browsable, listenable timeline of six decades of popular music. Each year’s station queues up 10 or so tracks; all you have to do is press play or skip (you’ll be doing a lot of skipping). Rdio subscribers get full songs. Everyone else gets 30-second samples. Really trust me on this: take an hour, maybe two, and work your way through the years. It’s the the easiest, and best, history class you’ll ever take. (Also note if you are from any other country than US just use an proxy it works as efficient as u being in the US 
