GTD contexts are great to get a todo list actioned, but there's a real problem for me when time is important.

I want a calendar just like that: One that I can throw a task at a certain day and time, and tick it off (when the time comes) to fade into completed-ness.

To me, this would be ridiculously useful for planning and rescheduling tasks. A real trusted, flexible system for tasks for which time matters.

For me it would be great if only for the moments when I need to get a task out of my head until later. Okay, you can set an event in iCal... But then to know that it or any other task has been done is important; that nothing has been left behind.

There, a possible manual iCal solution: but managing that and the clean-up of old events kills its usefulness.. surely someone out there has done this before? Ideally Apple would make this just how iCal works: Its flat todo list really has limited usefulness.

Anyone have any ideas, comments? Suggestions on how I could make this happen? I'm open to platforms (Mac/Win/Web) just for this simple functionality. In a perfect would, it would be great to sync with OmniFocus (a possibility when thinking of the task's Start and Due dates as the bounds of the doable event)