Application Menus in the panel
Many will argue that this is very OS X-like, and of course it is, but for myself and a lot of people having the application menus located outside of the window minimizes clutter nicely. To install it, just follow these instructions:
sudo apt-get install appmenu-gtk indicator-appmenu indicator-applet-appmenu
Add it to your panel by right clicking on the panel, choosing Add to Panel and then select Indicator Applet Appmenu
Log out and back in, and you should have global menus!