Those who need to draw complex diagrams on a frequent basis will know how important a good drawing program is. See if Dia fits the bill...
Dia is a simple but highly versatile structured drawing program to help you create the diagrams you need, from flowcharts and brainstorms to organizational charts and relationship diagrams. The author says that he hopes Dia will serve as a free alternative to Microsoft's Visio.
Dia is obviously a labor of love. It is easy to use, comes with extensive help and training, and provides a huge variety of diagram options that are sure to meet the vast majority of casual users' needs. There are more than thirty different "sheets", each of which provide the symbols and icons needed for different types of diagrams, for example, electrical, cybernetics and flowchart. Within each sheet type, the icons can be placed, resized and generally modified at will, and the resulting document then saved, printed or exported.
Every option is accompanied by rollover information. The graph itself, which Dia calls "the canvas", is also modifiable. You can change the specifications of this work surface, or modify the icons you use to create the diagrams, adding or removing them from categories or even creating new ones.
If there is any criticism that can be leveled at Dia, it is that the sheer volume of options makes it slightly overwhelming for the absolute beginner. It would also be very easy to miss out on some of its features purely because you didn't even know they existed. I would recommend that before starting out with the program, prospective users take a really good look at the manual provided to make sure they know exactly what the program has to offer.
Dia is an excellent program for anyone who needs to make any type of structured diagram.
