Drag highlighted cells (not columns nor rows). Drop pastes over the target cells. Ctrl+Drop copies over the target cells. Ctrl+Shift+Drop creates linkes over the target cells. Alt+Drop inserts new target cells removing the source cells. Ctrl+Alt+Drop inserts new target cells copying the source cells. Ctrl+Shift+Alt+Drop inserts new target cells, linked to the source cells.
From OO.org Forums. Need to remember this.