I don't have a palm pilot, but I looked at Justin's program. It seems to have all that anyone could want for a pre-planned measurement.
My measurements are rarely pre-planned to a point where I get two complete and uninterrupted rides from one end to the other. My last measurement went like this:
Arrived 40 minutes early for a meeting with the race director to show me the location of the finish line. Since I knew the basic circuit I did a loop ride beginning and ending at a reference point.
When the RD arrived, I measured the distance from the reference point to the finish line and found that I needed to remove 11 meters from the course. I did this at the reference point. Now I had completed one measurement of all the bits and pieces.
Then I did a standard start-to-finish ride, laying out the splits as I went.
A small final adjustment (second ride was shorter) finished the job.
I would not have been able to use a pre-planned program for this job.
I've also found that it is wasteful for me to calculate all the splits in a marathon measurement ahead of time. I generally calculate three or four splits ahead, and recalculate when I arrive at the last calculated point. I sometimes get off-course or otherwise screw up my plans.
When I am all done my final calculations look much like Justin's. For an example see:
SampleMeasurement.pdf