A choice on the contextual menu of the Microsoft Internet Explorer browser.
Some users (such as myself) browse the Web in an odd fashion: opening new windows for many of the links. Many sites have deep tree or network structures <cough>E2</cough> and cannot be browsed linearly in the Back button/Forward button style that browsers seem to prefer. So, if I see a link that I think will lead to a shitload of information, or that I want to save for later, I open it in a new window. Sure it costs lots of RAM, but that's the price I pay for missing nothing.
Sites that don't allow the user to right click just piss me off. See also right-click trap.