Microsoft Office has so many options that often the trickiest task is working out where to find the option you need -- something the Ribbon interface doesn't entirely solve. Office Online, the free browser-based version of the suite, now incorporates a "Tell Me" feature, where you can search for what you want to do using plain English and relevant menu choices will automatically be displayed.
The "Tell Me" feature has been in Word since the beginning of the year, but has now been extended to Excel and PowerPoint. Type a query such as "change line spacing" into the Tell Me box, which is found in the middle of the ribbon, and any matching menu options will be displayed. Like a search engine, results update as you type, so you often won't need to type a whole query. The drop-down menu also shows the most five recent options you've searched for, so you can repeat commands easily. And if you're a keyboard shortcut fan, you can use Control-' (apostrophe) to go straight to the search box.
Note this only works in the browser-based version -- it doesn't appear in the traditional desktop version of Office (whether you have Office 365 as a subscription or the boxed copy Office 2013 version). Desktop Office will search online help if your machine is connected, but in my experience it doesn't do a great job of finding the right options. Tell Me seems to work rather better, though that's probably partly because it only has a subset of the features of the full version. Regardless, it's a welcome improvement, especially for people who only use the Office apps occasionally. Hit the Microsoft announcement post for more details on how it works.
Get more done with Tell Me [Office Blogs]