Paper Planes - Relaxing web app that lets you throw paper planes with people across the world.
Spotify - Map shows when two people play same song at same time
Twin Strangers - Find your look like from anywhere in the world.
SoundCloud - Enjoy music & follow favourite artists
Twins or Not - Twins or Not is a decent and innovative application that allows you to compare your photo with other images and see if they match.
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