Since 25 February 2012, Spotify's users have been asking for song changes to show up in the OS X Notification center in a suggestion which has garnered 400+ votes.
On April 06 2013 I put together a small OS X application which implemented
that functionality. It did one thing and it did it well. The first release was a
whopping 70 lines (including comments!) and was contained in
The next day it was featured in TheNextWeb.
Since then, through new features and bug fixes, it's ballooned to 561 lines (plus third-party libraries!) while trying to stay to true to "less is better."