Display last and second last values from "populated" cells in a column. Say
A1:A10 with results in A11 and A12.

This could apply where you want to generate the number of hours of work in
each of the last two working weeks in a 10 week period. Not all 10 weeks will
have hours; some will be blank. The formula should remain true in another 10
week period with different weeks being blank. I have formulas which work well
in Google Docs Spreadsheet but I have not been able to modify them to make
them compatible with Excel.