yEd Graph Editor

This tool, created by YWorks, allows the user to create diagrams using either imported or manually entered data.

Automatic layout algorithms arrange even large data sets with just the press of a button. yEd is freely available and runs on all major platforms: Windows, Unix/Linux, and Mac OS X. 

This resource was suggested to BetterEvaluation by Rick Davies

Sources

yWorks. (2013). yEd graph editor. Retrieved from http://www.yworks.com/en/products_yed_about.html