I don't know if this is what you want, but KDE has a couple of GUIs to help edit the Start Applications menu (I don't know if Gnome has the same, but probably).
KAppfinder is a KDE GUI that can scan for apps to be added to the menu. Just enter the command 'kappfinder', or go to Settings -> Menu Updating Tool (KAppfinder).
The other one is the Menu Editor itself. You can run the command 'kmenuedit' or go to Settings -> Menu Editor.
(Note: Both binaries are located in /opt/kde/bin)