Raindrop.io - All your articles, photos, video & content from web & apps in one place.
Pocket - When you find something you want to view later, put it in Pocket.
Bookmark OS - Bookmark OS is like Mac or Windows optimized for bookmarks.
Diigo - Diigo is a powerful research tool and a knowledge-sharing community
Linker - Cloud based bookmark manager
Superdense - No text, just icons.