OmniGraffle
OmniGraffle is a diagramming application made by The Omni Group. OmniGraffle is built only for Mac OS X and the iPad. It may be used to create diagrams, flow charts, org charts, and illustrations. It features a drag-and-drop WYSIWYG interface. "Stencils"—groups of shapes to drag and drop—are available as extensions for OmniGraffle, and users can create their own stencils.
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