I remember creating a mobile app for Spotify before they did. It used a reverse-engineered API on a server to download songs and stream them to mobile devices. Most of my friends used it at my school. There were some issues with the server providers and eventually Spotify disliking the fact that the server constructed DRM free music files and stored them temporarily on a disc.

Eventually, Spotify released its official mobile apps and a web player so the project had no use. But it was fun times, it was really marvelous how anyone could find their favorite music from the service and listen to them in good quality without a torrent connection.

Nowadays, I think all those friends who used the hack are Premium subscribers.