I can’t believe Omni-automation has been out for so long and I haven’t talked about it.
The tl;dr of the site is that Omni Group recently (as in six months ago) supercharged the automation capability of all their apps (OmniFocus, OmniGraffle, OmniOutliner, OmniPlan), by giving them a really robust Javascript Core framework. That sentence will either send you to sleep, or make you quite excited, and that reaction will tell you whether you care an inch for this post or not.
With your expectations set, let’s see how I can develop a really simple Javascript plugin for OmniFocus in about half an hour.