That sounds like the kind of thing that would be straightforward to do
in a Google Chrome Extension "content script" or a Firefox
Greasemonkey script. That would give you the control to decide if you
wanted it to *always* happen. (There may even already be one that can
be customized to fit your preferred way of working.)
Becoming comfortable with browser scripting can really change how you
view the web.
http://code.google.com/chrome/extensions/content_scripts.html
http://wiki.greasespot.net/Main_Page
But a multiple button mouse seems like the easiest/most flexible solution. :-)