"ReCo takes music artist names, creates a playlist of tracks from related artists, adds links to play those tracks in Spotify."

"Which means it's become pretty easy to put together an app that takes a list of artists provided by the user, generates a playlist and links the tracks to Spotify. Like this: ReCo."

"Here at the Echo Nest just added a new feature to our APIs called Personal Catalogs. This feature lets you make all of the Echo Nest features work in your own world of music. With Personal Catalogs (PCs) you can define application or user specific catalogs (in terms of artists or songs) and then use these catalogs to drive the behavior of other Echo Nest APIs. PCs open the door to all sorts of custom apps built on the Echo Nest platform."