Google Contacts - Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.
Spotify - Map shows when two people play same song at same time
FullContact Card Reader - Automagically scan biz cards into LinkedIn/Gmail contacts
SoundCloud - Enjoy music & follow favourite artists
Nextcloud Contacts - The Nextcloud contacts app is a user interface for Nextcloud's CardDAV server.
Last.fm - The world's largest online music service. Listen online, find out more about your favourite artists, and get music recommendations, only at Last.fm