Open in new window.
Quite a long time ago, I stopped clicking on links with the left mouse button. Too often, this resulted in a new browser window. Sure, Firefox has the option to open a new tab instead of a new window but still it is not obvious to me, what a left click on a link does. Will it open a new window/tab or will it change the page?
What I want (and I suspect most users want that) is that whenever I click a link, the same happens. It’s not important to me wether this “same” is opening the link in the current tab or in a new tab. It just has to be consistent.
To get this kind of behaviour, I no longer use the left mouse button but the middle one (or Cmd-[Shift]-Click on Safari/Mac). This always opens the link in a new tab. In my case, in a new tab in the background. With this setting, I can open a list of links (think of a newsticker with links to the articles) before leaving the index page.
There are two drawbacks with this method:
If I want to follow only one link, I have to close the page I come from.
I completelly lose the back button in the tab/window, I always have to use the browser history.
Having to close the page might be annoying but I got really fast closing pages, so this is not a big problem for me. Loosing the back/forward buttons is a drawback. One that would be easy to overcome for the browser developers: Opening a link in a new tab/window could simply copy the history from the origin. Until browser developers support this I have to live without the back button.