TubeLister - Generate a YouTube playlist from your opened tabs.
Vidooly - Get deeper analytics of any YouTube channel or video
OrganizeTube - Create video playlists from Youtube, Vimeo and other sources
SimilarChannels - Find similar YouTube channels, discover new channels based on your interests, create your own YouTube collections with your favorite channels.
Learnamic - Free and paid K-12 learning resources from hundreds of providers, including educational apps, YouTube videos, online classes, printable worksheets, and more.
YouTube Trending - Making it easier to find viral videos