AbTest.io - A free url shortener with A/B testing features
Spotify - Map shows when two people play same song at same time
GoodUI Evidence - People's A/B test results that show which UI ideas work best
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
PreFlight - Preflight is an Automated Web Testing tool. Allows everyone to automate Web UI tests.
SoundCloud - Enjoy music & follow favourite artists