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.
Tuned Rocks📺 - Discover🔎 curated Youtube videos 24/7
Musicroamer - A visual Pandora for discovering new music
Vidlis - Create music playlists from YouTube videos.
LivePlasma - Discovery engine map for books, music, and movies