One of my goals as a Windows 7 user is to be as efficient as possible -- simply put, it saves me time and energy, which I can then devote to getting more done. To that end, one of my most often-used shortcuts is "Recent Places."
Recent Places can be found when you click on the "Folder" icon on the Taskbar. The Folder icon displays the contents of your hard drive. In the upper-left corner is a grouping of items under "Favorites". The last one of these should be "Recent Places", which you can see in the screenshot here (it's outlined in red).
Recent Places, when clicked, opens up a group of folders to the right. These are folders you've recently altered, usually by adding content of some kind, whether it be pictures, music, documents or whatever. So, rather than having to wade through your entire hard drive of files to retrieve something you've used recently, just use Recent Places. I think you'll love it, once you start using it.
One note: Recent Places works best if you have a proper folder structure in place. I've written a step-by-step tutorial on how to do just that. Check it out.