Maker Swipe File - 100+ high-performing Tweets to help you grow your audience
Bookmark OS - Bookmark OS is like Mac or Windows optimized for bookmarks.
Narrow - Narrow helps you build a targeted audience and increase your influence on twitter.
Bookmark It - Create awesome notes on YouTube videos
Tweetflick - Save, organize & find Tweets to get the most out of Twitter
PageMarker - Save, organize, annotate and revisit your bookmarks