I can always count on GigaOm’s WebWorkerDaily for software gems. WebWorkerDaily » Archive Zen Computing: Toward a Distraction-Free Desktop provides a good list of editing tools that are distraction free.
I particularly like JDarkRoom (beware it doesn’t use all the standard Mac key sequences for example: save is Ctrl-S instead of the usual Command-S) and Backdrop. The irony/BlackHumour behind using these applications on a 23″ G5-based machine is big, but they really help me focus on one task at at time.
Back to the Future: The more I dig into these zen apps, the more that I end up firing up vi in Apple’s terminal ;-) vi may be ancient, but it really really works. Just set it to “green on black” in Terminal–>Window Settings… “et voila” totally zen, useful, powerful, and majorly productive.
Zen Reading App Tofu is great for reading.