Diagram Designer doesn't need much introduction. With this program you can design and create any flow diagram, as if it were a specific graphic editor, for your work and presentations.
Among its main features you will find editable object templates, importing/exporting images in WMF, EMF, BMP, JPEG, PNG, MNG and PCX formats, a plotter to graphically show mathematical expressions, a very simple calculator to solve equations, and compression and optimization systems to reduce the size of the designs as much as possible (they are still images).
On the Diagram Designer author's website you can download a translation pack with a lot of languages.