The Jump-list stuff has been on my list for a while:
What we are facing here is:
Adding actions to the appmenus: new tab (browser), new note (for tomboy or gnote) or pause (for the media players)
Adding document shortcuts in the appmenus: 4 most recent documents and other most used (in the last x days) documents with gedit
I already have a solution for the second and the implementation is there but relies on zeitgeist since a lot of apps don't store their actions into gtk.recentmanager (we also are looking into
https://live.gnome.org/GTK%2B/GtkRecentManagerAndZeitgeist) and most used can only be calculated by something that tracks history like Zeitgeist.
I am up for the task of implementing this feature if a designer and a technical expert can dedicate some time to walk through concept with me.
Cheers
Seif