I am totally addicted to "linkification" and "tab mix plus." My other favorite extensions are "form saver," "image shack right click," "pdf download," "reminderfox," "search engine ordering," "unhide passwords," "foxy tunes."
I just tried "refresh blocker," to deal with the web pages that INSIST on forcibly refreshing whether you WANT them to or not. It works most of the time.