I attended a conference where Chris Parkes gave a quick demo on the new features of the 2007 Office system... nothing new there you may say... well, Chris briefly showed that if you wanted more space on your screen (perhaps to review a document), you can minimise the ribbon by either double clicking on the selected menu or press pressing Ctrl-F1.  If I had read Jensen Harris's blog, I would have known about this already, but a very useful feature indeed.