TweepsBook - A better bookmarking tool for power Twitter users that you can use to filter, organize and bookmark tweets on your liking.
ilo - Premium Twitter analytics
Tweetflick - Save, organize & find Tweets to get the most out of Twitter
Accountanalysis - A tool to evaluate Twitter accounts
Twitter Bookmarks - Create shortcuts to your favorite users/tweets on Twitter
Tweetastic - Better Twitter analytics, scheduling and more