I've been dreading a project that may require in-system calibration.  Here's
the scenario - I'm using some cheap, poor tolerance thermistors and
potentiometers in a controller.  I have a number of these built up, and
found their behavior changed quite a bit from unit to unit, ostensibly
because of tolerance variations.  (I'm not really sure)

I could tighten the tolerance by spending money, but the circuit must be
absolute minimum cost.  So I'm imagining a system that:

1.  Does a final check on resistances in the circuit  (and maybe a quality
control check too?)

2. Calculates two or three constants based ont he resistances in the circuit

3. Creates the proper code (would it have to COMPILE or just modify the
right bits in a hex file?)

4. Squirts the program into a PIC either in- circuit or just before
insertion

It sounds really complex and capitol-intensive.

Has anybody worked with these before?  Is there commercial equipment that
does this task automatically?