I wonder sometimes how people can use Internet Explorer. Even putting its bugs, security issues, and lack of, well, usefulness (when one considers the functions provided by Mozilla Firefox and its extensions) aside, the lack of a tabbed browsing feature is easily my biggest frustration when forced to use an IE-only computer. (This doesn't happen often; all the computers I've ever used at USF have Firefox as an option.)
I hear from some users who prefer IE that they don't "get" tabbed browsing. "I have no use for it," they say, "and it just confuses me."
Personally, I'm a Mozilla Camino user, because I prefer the natural OS X Cocoa interface to the Firefox XUL one -- if I'm using a Mac, I want my software to look and behave like one, too. Camino is, for most intents and purposes, exactly like Firefox, so I'm not committing a heinous act of skullduggery by pimping Firefox while using Camino.
I concluded long ago that the preference for tabbed browsing (which was, to set the record straight, introduced in 2001, first with the original [and quietly departed] Mozilla browser that was the outgrowth of Netscape Navigator, and more publicly with version 6 of Opera) is inversely correlated to the user's ability to maintain attention on any given subject. I was a big Opera user in the early part of this decade, before I picked up Phoenix (which became Firebird, which became Firefox). The need to open dozens of article pages for printing at one time made Opera's tabbed browsing a godsend.
Since then, I've never found myself without at least a few tabs open in whichever browser I'm using at the moment. Today, I'm typing this article on my Macbook: Camino's tabs, from right to left, show abandoned or still-active pages of my Yahoo! Fantasy team, a deleted thread from ONTD, a half-read Fark thread about the Bible's evolution, the features page to Justin Frankel's REAPER audio production software, a page about the Antares Microphone Modeling software, the Wikipedia page of Chief Justice Earl Warren, this Movable Type page, a Fark thread on that old Honda Rube Goldberg ad, a page on the history of tabbed browsing, and the Opera homepage.
Sitting next to the Macbook is my PC monitor and keyboard. The Firefox screen has even more open tabs, most of them hosting pages I've still not yet read, and calculating how I got to all of them is an amazing study in my absolute lack of anything resembling an attention span.
Realize that I have been doing all this while watching the Browns game on my television and listening to the radio feed of the Browns broadcasters, via their Rochester, NY AM affiliate.
It started about four hours ago. Seeking an explanation of the Harlan Ellison controversy mentioned at John Scalzi's excellent blog. Apparently Ellison grabbed someone's boob at this year's World Science Fiction Convention.
So I went to the Ellison Wikipedia entry, which explains the situation -- but not before I was caught up in Ellison's pen name, "Cordwainer Bird." The editor helpfully explains a cordwainer is someone who makes shoes from Cordovan leather. But what is that, exactly?
I click through to Cordwainer. From there I click to a discussion of Leather and from the discussion of "Leather in popular culture" there, to Judas Priest singer Rob Halford who first popularized the use of leather clothing in rock music.
The Halford article explains he once filled in for Ronnie James Dio who made a guest appearance on the Queensryche album Operation: Mindcrime II. (Middle-clicks opened new Wikipedia windows to articles like "Latigo" and "Neatsfoot oil" in the meantime.)
Ed. note: at this point I save the text file and start typing this article on the PC, where it's much easier to copy and paste these URLs.
Operation Mindcrime: II takes me to Operation: Mindcrime and then to the main Queensryche page. From there I split out tabs for Progressive Rock and the Queesryche album Empire which are flipped back and forth.
A half-dozen tabs from the Progressive Rock album get popped out, including one on the Genesis album The Lamb Lies Down on Broadway, prog rock supergroup Asia, and Finnish metal band Nightwish (none of which have been read yet).
Prog rock features odd instruments including the Mellotron, so I opened that page which had as an external link an ingenius project where a dude built his own Mellotron using fourteen Sony Walkmans (Walkmen?). The Wikipedia entry for Antoine de Saint Exupery is on a tab, too, though I can't even at this point remember why. I think it's related to the article about Genesis somehow -- that tab is open as well.
One of the Mellotron pages led me to open up the entry for the Beatles' White Album. That's when we really get off-track. The next hour or so, I'm reading Alan Pollack's articles about individual Beatles songs -- particularly the Side One, Track One songs. This, of course, all resulted from me clicking through to the entry, and Pollack's article, on Back In The U.S.S.R. (my favorite Beatles song).
So I open up all the individual pages to songs on the White Album, and then to the article on Danger Mouse's Grey Album, and then to Danger Mouse himself, then to Danger Mouse - Cee-Lo collaboration Gnarls Barkley, and so on.
The article on Balilikas (sp? don't feel like checking anymore) is open. The article on Beatles vocal technique Double Tracking is open. And a bunch of unread articles on individual Beatles songs are still open.
And that's how one goes from Harlan Ellison to an entire afternoon wasted reading fascinating things about the Beatles. And yeah, I'm going to the doctor soon about this attention deficit thing. For now, I'm going to try and work my way through the already-open tabs, and the Browns game has 30 seconds left.

I won't bother to point out that you could be just as easily brain-ADHDled using multiple IE windows... In fact, XP's default interface groups multiple program windows (including IE's) into single tabs toolbar tabs that then expand when clicked. Not quite the same as FF tabs, but nearly so. Plus, the real value of the tabs lie strictly in organization, not actual usage.
And that said, I'm a regular FF user, going back to the last Firebird release. For the rare instances when I'm on a Mac, I'll switch on the tabs in Safari. It's all just a semantic preference, coming down to where you prefer to slide your mouse.