I was excited about OmniOutliner, then even more about KGTD (scripts to automate based on GTD) and now I might have reached my next heaven with Incubator http://mindcad.com/ ($49).
- It is very easy to add items
- the layout is automatic
- one document can have several "sheets" (@errands, @home, ...)
People are different, and I like those diagrams.
For me it is easier to remember, to recognize and to plan this way.
Just as an inspiration, admitting that I started with this software only some few days ago.