This app will map out where your friends are located across the world.
More importantly, it provides practice in reading developer documentation.
In particular:
https://developers.facebook.com/docs/facebook-login/login-flow-for-web-no-jssdk/
https://developers.google.com/maps/documentation/javascript/tutorial#HelloWorld
https://developers.google.com/maps/documentation/geocoding/#GeocodingResponses