Two of the extensions for firefox for firefox I find most useful are vimperator and tab mix plus. But vimperator 2.0 is decisively incompatible with tab mix. After suffering without tab-mix for a while - as giving up vimperator is not an option - I came to the realization that firefox 3 had swallowed almost everything I use tab mix for, except for the one thing I really missed: having links to external sites open in a new (backgrounded) tab.

So I put together a greasemonkey script out of bits and pieces of a couple others that didn't do exactly what I wanted. It works almost everywhere, but a couple sites (like Google Reader) already open stuff in tabs but don't background the tab. A simple about:config setting fixes them:

browser.tabs.loadDivertedInBackground;true

(note: this does prevent firefox from taking focus when external links are clicked)

Having links work this way is great for going down a page with a ton of links and clicking interesting stuff to read in chunks, and it confuses the heck out of people that get near my browser - they click on stuff a zillion times but the page doesn't change, and they don't notice all the tabs they've opened.