[say that five times fast]
With MSIE (and I think Netscape), if you hold down the shift key while clicking on a hyperlink, the hyperlinked page opens in a new window.
This is especially advantageous when the original page is a list that's created 'on the fly' such as the list of forums or threads in a forum (or the "Harbour Lights" list on e-bay).
This is time-saving because when you want to go back to the list, you simply close the new window. You don't have to wait while that list is recreated from scratch.