The Omni Group

If you're a new OmniGraffle user or just new to using OmniGraffle, these walkthrough files will acquaint you with the basic principles of how diagramming works in OmniGraffle, as well as put you through the paces of how the drawing tools work, including the new Bezier Pen Tool, Magnet Tool, the improved Style Brush and more.
Requirements: OmniGraffle or OmniGraffle Professional (version 4 or above). Mac OS X 10.3.9 "Panther" or later.

OmniGraffle is capable of creating a wide variety of document types, ranging from a map of the solar system to phylogenetic trees to web color charts to the ever-popular "Very Important Process" flowchart. These samples are included in this download, showcasing just how snazzy and elegant OmniGraffle can make your documents look, as well as flexing some AppleScript muscles in case you have to map out gravitational forces or navigate your way through the dangers of the Krebs Cycle.
Requirements: OmniGraffle or OmniGraffle Professional (version 4 or above). Mac OS X 10.3.9 "Panther" or later.

Ronán Conroy has created this OmniGraffle template based on the CONSORT guidelines, showing some useful examples of how the template can be used to report clinical trials of different sorts. Thanks go out to Dr. David Moher of the CONSORT group for permission to reproduce the diagram.The template has two layers. The second layer is non-printing, and contains text which is in the CONSORT template but which is not used in actual clinical trial reporting. It also contains the URL from which the CONSORT statement can be downloaded.

Pie charts, bar charts, spirals, arcs, pointed stars, all scripted out by Peter McMaster (whose surname is becoming more and more appropriate), and there's also a page there for a regular polygons stencil, which is, well, regular. Well, not everything can be special (not to say that the AppleScripts are irregular, it's just that -- well, there's a joke in there somewhere).

Jesse Shanks has posted an article laying out how he used AppleScript to turn OmniGraffle into a news reader - a download link to the script is included.

It's a car, it's a casino, it's that city in the small principality south of France! Actually, it's not. Christian Fries has made a cool AppleScript to generate a Monte Carlo simulation, which provides approximate solutions to a variety of mathematical problems by performing statistical sampling experiments on a computer.

Nick Finck over at Blue Flavor took the keyboard shortcuts document that comes bundled in OmniGraffle (and can be found in the Help Menu) and compacted it into a printable "cheat sheet", in case you'd like to have a hard copy to reference whilst using OmniGraffle. Neat!

Apparently Canada simply wasn't large enough a project, so John Oram took on the entire world. A set of OmniGraffle documents with all the major geographic areas done up, replete with country names in English as well as their native language, all set to scale.

Seth Friedman has created a unique set of OmniGraffle documents that lay out the handy lines to create origami creations such as the Black Skimmer, Click Beetle, Dove and more.

Fraser Speirs took some time and care to make a Ruby script that diagrams out Git repositories. The script itself and example can be found not ironically at GitHub. Links are to the left over there.