Is it possible to add a quicklist to the Libreoffice Writer icon in the Unity Launcher showing my most recently opened documents?
The feature you're talking about is called "dynamic quicklists", which is where a program generates quicklists based on information it has about your documents. Right now all the quicklists you're seeing are "static quicklists", which is just a list.
So for example Firefox could have "Recently Closed tabs" or "Last visited", and that sort of thing. While support for dynamic quicklists is in Unity, programs still don't really take advantage of the feature just yet.
Hopefully LibreOffice and other projects will support this in the future but right now this is on a per-program basis.
You can manually add your favourite files in the Quicklist of a Launcher-icon so that it looks like in this screenshot
I describe the way for Precise Pangolin using Ubuntu Tweak (Version 0.7.0):
Open Ubuntu Tweak > QuickLists Editor > click on LibreOffice-Writer on the left side > click on the little Plus-symbol > Enter the Name of the file (it's the name that will be shown in the Quicklist) > In the Command-field enter:
Note: I had to login again to make the behaviour of starting a favourite file from the Quicklist work properly.
Concerning LibreOffice Calc the command would be:
Concerning Gedit the command would be:
This solution also works when - for privacy reasons - someone has Zeitgeist totally disabled or just textfiles and/or spreadsheets excluded from activity-logging. Without Zeitgeist enabled, the Dash will show no Recently Used Files.