Visio is one of the most common apps for Windows that makes similar diagrams, but I really like http://www.gliffy.com http://www.gliffy.com and http://www.mindm

Visio is one of the most common apps for Windows that makes similar diagrams, but I really like http://www.gliffy.com http://www.gliffy.com and http://www.mindmeister.com http://www.mindmeister.com. Both are webapps and would work equally good on Windows, Mac OS, or Linux.