Bookmark OS - Bookmark OS is like Mac or Windows optimized for bookmarks.
BookmarkSheet - Your bookmarks in Google Sheets
Annotate.tv - Optimize your learning on YouTube
Raindrop.io - All your articles, photos, video & content from web & apps in one place.
Siimpl Bookmarking - Start collecting and organizing what interests you
PageMarker - Save, organize, annotate and revisit your bookmarks