Just Click to Open Behind
You may find yourself (sounds like a Talking Heads lyric) staring at a webpage that contains many links that you want to open in background windows. You could press a key combination every time you click the links to force the open behind option, or simply click this bookmarklet to go into open behind mode.
If you click and hold on the text of the button below and drag it onto your bookmarks bar, it creates an Open Behind button. Then click the new button to re-render the page in open behind mode. Now, an ordinary click will open a new window behind the current one. To go back to normal clicking mode, simply refresh the current page.