TubeLister - Generate a YouTube playlist from your opened tabs.
Gnoosic - Even if you don't know what you are looking for - gnod will find it.
Vidlis - Create music playlists from YouTube videos.
Musicroamer - A visual Pandora for discovering new music
Tuned Rocks📺 - Discover🔎 curated Youtube videos 24/7
TasteDive - TasteDive recommends similar music (musicians, bands), movies, TV shows, books, authors and games, based on what you like.