As most GTD applications are usually database files of one kind or another (even Mail.app) I turned to FM Pro to build my own. The combination of Quicksilver to trigger an applescript to open my database and create a new action with the cursor waiting in the action field to type is the really fast. I use "option - n" as a QS trigger and just start typing.

As dates are easily selected from pop-up menus in FMP there are no issues in planning ahead for reminders etc. I use three levels of fields for nested projects: 1) "Horizons" for categories such as Work, Home, Personal, 2) Projects and 3) Sub-projects. This seems to be enough for all my needs.

Anyone else using Filemaker for GTD?