Linkman - Linkman Pro allows for managing large amount of URLs in its own database.
LinkLocker - LinkLocker is a lightweight bookmarking service with an emphasis on privacy.
Firefox Sync - Bring your Firefox bookmarks, tabs, or passwords wherever you go with Firefox Sync. Share between computers and mobile devices. Get Firefox now!
Raindrop.io - All your articles, photos, video & content from web & apps in one place.
Diigo - Diigo is a powerful research tool and a knowledge-sharing community
Quicklinkr - Organize & Share your favorite links. Discover & Save new ones.