Join My Playlist - Listen to music live together with your friends in Spotify.
SimilarChannels - Find similar YouTube channels, discover new channels based on your interests, create your own YouTube collections with your favorite channels.
Parallel - Listen to music with friends over Spotify at the same time
Vidooly - Get deeper analytics of any YouTube channel or video
TuneMeet - Chat with people who are listening to the same song
YouTube Trending - Making it easier to find viral videos