Just one of several great, easy-to-use programs from The Omni Group, OmniGraffle creates diagrams and charts with a "drag and drop" philosophy. Within a few minutes of exploring the program, you will be able to create great charts, office layouts, project outlines, family trees, etc. The best part of OmniGraffle may very well be the inclusion of "Network Stencils" (pictured below) that include graphics of the latest Apple products to be dragged and dropped onto your canvas.
While OmniGraffle is not a freeware, the trail version is available for download here and allows users to add up to 20 items/shapes/stencils to each project.
OmniGraffle Professional is also available for trail download through the web site. The Pro features include: Tables, Advanced Scaling, Shape Combinations, XML Import/Export, SVG Export, Multiple Page Documents and many more interesting features to check out.