Altarsoft PDF Reader - Altarsoft PDF Reader is a simple to use PDF files management program that allows its users to view PDF files, encrypt the files and even annotate these files as well.
Xmind - Xmind is a brainstorming and mind mapping application.
eXPert PDF Reader - eXPert PDF Reader is a free to use PDF reader and views for the Windows operating systems.
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.
Cool PDF Reader - Just like its name Cool PDF Reader, this small PDF reader is a really a cool PDF reader for viewing, reading and editing PDF files for free.
Coggle - Coggle is a simple, beautiful, powerful way of structuring information.