Raindrop.io - All your articles, photos, video & content from web & apps in one place.
Linkman - Linkman Pro allows for managing large amount of URLs in its own database.
LinkAce - A selfhosted bookmark manager with advanced features.
Pocket - When you find something you want to view later, put it in Pocket.
Bookmark Sidebar - Adds a toggleable sidebar with all your bookmarks at the edge of your browser window.
Diigo - Diigo is a powerful research tool and a knowledge-sharing community