How to hide the Ribbon menu in Microsoft Office applications
The new Ribbon interface on Office 2007 and 2010 is quite fancy, and once you get used to it, it's a lot of fun to use. One of its few downsides is that it's tall – far taller than a "traditional" menu. If you're working on a netbook or are otherwise pressed for screen space, it can sometimes be handy to collapse the Ribbon and make it as compact as a regular menu.
To collapse it, simply double-click one of the Ribbon's tabs, such as "Home". The whole thing will instantly shrink down to the line of tabs. Clicking a tab will temporarily expand it back. If you'd rather do the same thing using the keyboard, simply hit Ctrl+F1 (that's what I normally do).