Gnome Globalmenu

Global Menu is the globally-shared menu bar of all applications launched in your desktop session.

In other words, it works more like the menu bars you see on a Mac. Its very useful and works brilliantly. Although support for many apps are missing, its in constant development and improvements are likely to be seen very soon. The installation guide for the app is quite exhaustive and doesnt need any explanation, so I'll direct you to the guide: www.code.google.com/p/gnome2-globalmenu/wiki/InstallingonUbuntu

Okay, so after you have installed it, you need to add this applet to the panel. Right click on the GNOME panel, select Add to Panel and then select Global Menu panel Applet from the list. Thats all. Try it out. And of course if you dont like it, you can remove it the usual way by typing sudo apt-get remove gnome-globalmenu