oh man do I need this:
Aging Tabs in Firefox: http://www.lifehacker.com/software/firefox-extensions/download-of-the-day-aging-tabs-firefox-212525.php
I'm a tabaholic/tab-pack-rat
pretty cool. i keep a tight reign on my open tabs, tho, so this isn't for me. but i absolutely love FLST (focus last selected tab) https://addons.mozilla.org/firefox/32/