TubeLister - Generate a YouTube playlist from your opened tabs.
NOISESUPPLY - Pandora for SoundCloud
OrganizeTube - Create video playlists from Youtube, Vimeo and other sources
Vidlis - Create music playlists from YouTube videos.
NewPipe - NewPipe is a lightweight YouTube front-end for Android.
Playlist Machinery - Tools that help you create & organize your Spotify playlists