Vidlis - Create music playlists from YouTube videos.
OrganizeTube - Create video playlists from Youtube, Vimeo and other sources
DiskyT - Youtube playlists done right
Playmoss - Create playlists from YouTube, Vimeo and SoundCloud
NewPipe - NewPipe is a lightweight YouTube front-end for Android.
JuniorTube - Curate YouTube playlists. Remotely push them to kids iPads.