When you drag highlighted text to the desktop, you create a text clipping. And when you drag a URL favicon to the desktop, you create a .webloc file—a document that, when opened, launches the saved URL in your default browser. Hints reader llee frequently uses both clippings and .webloc files, and discovered a clever way to copy those files' contents to the Mac's clipboard quickly.
Start by dragging the clipping or .webloc file towards the upper-right corner of your screen. As you drag, trigger Spotlight's search window. (The default keyboard shortcut is Command-Space.) When you drag the item over Spotlight's text-entry field, your cursor will turn into a green and white plus sign. Release the mouse button, and the contents of the file—whether a URL or a text snippet—will appear in the Spotlight search field. The text will already be selected, so a quick Command-X (or Edit -> Cut) will cut the text from the Spotlight field into your clipboard.
There's a reason you have to trigger Spotlight after initiating the file-drag with good reason: if you open Spotlight's search box first, and then start dragging, the search box will disappear again. And the tip uses Command-X (or Cut) instead of Command-C (or Copy), because otherwise our text will still be in the Spotlight box the next time we go to use it.
Also note that, if you double-click a text clipping in Snow Leopard, you generate a window from which you highlight and copy its text. Copying text from clippings has a long and twisted history in OS X: You couldn't do it at all until 10.3, and then you had to copy the entire clipping or nothing at all. In 10.4, you could select sections of text (but your selections were, strangely, invisible). Finally, in OS X 10.6, you can not only highlight multiple sections of a clipping to copy—you can see the highlights as you make them.