Bookmark It - Create awesome notes on YouTube videos
Bookmark OS - Bookmark OS is like Mac or Windows optimized for bookmarks.
Twitter Bookmarks - Create shortcuts to your favorite users/tweets on Twitter
Siimpl Bookmarking - Start collecting and organizing what interests you
POAP - POAP is a new way of keeping a reliable record of life experiences.
Rewind Bookmarks - Your bookmarks, by date, with thumbnails and instant search