Tweetflick - Save, organize & find Tweets to get the most out of Twitter
Xmind - Xmind is a brainstorming and mind mapping application.
Twitter Bookmarks - Create shortcuts to your favorite users/tweets on Twitter
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.
TweepsBook - A better bookmarking tool for power Twitter users that you can use to filter, organize and bookmark tweets on your liking.
Coggle - Coggle is a simple, beautiful, powerful way of structuring information.