UMLGraph - UMLGraph is a professional automated drawing tool that allows the designers the declarative specification and drawing of UML class and sequence diagram.

SmartDraw - Instead of starting with a blank screen, SmartDraw gives you the exact template you need.

yEd - yEd is a free desktop application to quickly create, import, edit, and automatically arrange diagrams. It runs on Windows, Mac OS X, and Unix/Linux.

Signavio - The Signavio Process Editor was created in order to be very intuitive and easy to use.

Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.

Pega - Pega provides business process and customer relationship management solutions for organizations.