I'm just beginning to work on my own GTD system, and I'm using OmniOutliner 3 Pro for a good part of my action list management. Since David (Allen, author of ::amazon("0142000280/merlinsblog-20","Getting Things Done")::) recommends using your calendar to manage the hard landscape, I have appointments and such in iCal.

Today I wrote a short AppleScript that pulls today's appointments from iCal into an OmniOutliner document called Today.oo3, stored (by default) in ~/GTD/. It's nothing fancy, and I'd be open to suggestions if anyone tries it and has ideas.

The script can be found here:

http://redmonk.net/files/makeTodayOutline.txt

Bugs: for some odd reason, the script may grab all-day events from the next day.

Next action: add a column for the time of the event.