yEd can be used to quickly and effectively generate high-quality diagrams.
You can create diagrams manually or import your data for analysis. Their automatic layout algorithms can arrange even large data sets with the press of a button.
You can import your data from an Excel spreadsheet (.xls) or XML, create diagrams with ease via an intuitive user interface, automatically arrange your diagram elements, and export bitmap and vector graphics as PNG, JPG, SVG, PDF, SWF.
Supported diagrams include BPMN Diagrams, Flowcharts, Family Trees, Semantic Networks, Social Networks, and UML Class Diagrams.
Support is available on the official website, including forums, manuals, and video tutorials.
Here is one of those tutorials:
Before downloading and installing, you can try it free online with yEd Live.