One billion. That’s the amount of dollars that the Cash For Clunkers program devoured in just a week. That’s also the amount of dollars you likely wish you had. And believe it or not, that’s the amount of times Mozilla’s Firefox browser has been downloaded since its inception in 2004. Just as July drew to a close, the one billionth download of what’s likely the web’s most soaring browser in terms of popularity took place. As we detailed in our review of Safari 4, Firefox holds a special place in the hearts of