Selection Search - With this extension you can easily search for text you have selected.

Xmind - Xmind is a brainstorming and mind mapping application.

Swift Selection Search - Swiftly access your search engines in a popup panel when you select text in a webpage.

MindManager - With MindManager, flexible mind maps promote freeform thinking and quick organization of ideas, so creativity and productivity can live in harmony.

Context Search - Context Search is a Firefox extension that expands the context menu's 'Search for' item...

MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.