I recently wanted to transform a summary table of the form:

into a table with rows of (activity, date, value) so that I could add columns for year and month and then analyze the data using a pivot table.

It turns out that you can do this with another pivot table, yay! I followed this tutorial to convert my summary columns into data rows using Microsoft Excel 2010.

1. Press Alt-D, P to get to the secret pivot table wizard that's different from the one you get from Insert > Pivot table.
2. Choose Multiple consolidation ranges. Click Next.
3. Choose I will create the page fields. Click Next.
4. Select the range and add it. Go through the rest of the wizard to create a pivot table.
5. Remove the row and column fields.
6. Double-click on the total.

You should now see a table with the data from your crosstab.

Neato! Pivot tables are even cooler than I thought.