The potential shown by The Omni Group's OmniGraffle 1.0 (Reviews, October 2001) is fulfilled in the more mature OmniGraffle 2.0.2. This version of the OS X-native chart-creation program includes enhancements such as the ability to implement AppleScripts and incorporate hyperlinks in charts. There are also several cool new design tools.
OmniGraffle is generally reliable--though one inexplicable crash served as a reminder to save work often--and it was fairly easy to use, once we got the hang of its unique interface. The printed manual walks you through the creation of a simple diagram and gets you acquainted with OmniGraffle's tools, panels, and palettes. Via this interface, you can generate and color shapes, insert text, connect objects, and otherwise structure your chart.
For organizational pros and developers, OmniGraffle's more-advanced new features include support for Project Builder files. The comprehensive Selection panel gives you myriad fine-tuning options, and you can export finished charts in many standard formats, such as JPEG, GIF, TIFF, and PDF.
As in version 1.0, the Auto Layout tool, which you can use to reorganize a chart in a way that "makes sense" to the program, often had us scurrying for the undo command. Complex hierarchical charts aren't served well by this tool--it can misinterpret parent-child relationships and randomize a chart's order.
Macworld's Buying Advice
If you have a diagram to draw in OS X, OmniGraffle 2.0.2 is for you. You may have to invest some time in learning the program, but you'll be more than compensated by its organizational wizardry.