WatchWindow Extension
From Apache OpenOffice Wiki
Watch Window
With Watch Window Extension, you can add a Watch Window, which keeps the value of the monitored cell on the screen, no matter where the change is made.
http://extensions.services.openoffice.org/en/project/watchwindow
1) Start OpenOffice.org Calc
2) Select Tools - Detective - Display watch window
3) Add a cell that you want to watch with "Add cell" button