I have a column of data and I need to sum the values in adjacent cells when
they are bounded before and after by cells that contain a value of 0. Then I
need to sum the next group of cells bounded by zeros. So I want a column with
subtotals rather than one total. The number of cells in one group may vary.
I've tried using the sumif function, but what I want doesn't seem to quite
fit.

I'm using Excel 2007.