Once the Spotlight field is active, begin typing the file name you are searching for. Once it appears, use the arrow keys (or mouse) to highlight the file. Now, hold the Command key and click the file. Finder will open a new window with the file's location. From here, you can drag this file to a new folder, your email, or wherever you need it.
A similar tip can be applied when using the Recent Items list, located from the icon in the Mac OS X menu bar. Navigate to the Recent Items list and hold Command. You will notice that the menu items change to reflect that the item will open in Finder (instead of opening the actual file).