I need to create a list that is associated with a particular cell where I can
sum the values in the list and display the sum in the associated cell.

For example, if I right-click on cell A1, I would like to be able to
create/edit a list that can give me the sum of its values in cell A1.

It would be like creating a comment balloon where instead of having a text
area, I would have a small list and whatever calculation I do to that list
the result would be displayed back in the cell associated with it.

I have done extensive search on this and have found nothing like this, but
if anyone knows if I can do this and would like to help me, I would
appreciate it.

Thanks.