Well, I'm finally thinking about replacing my partridge-hit holed 21" viewsonic with a new monitor as I'm tired of erasing the same white spots that aren't really there from each photo

with one of these monster displays -
http://accessories.us.dell.com/sna/p...530&lid=627063 - last year's Dell 30" S-IPS panel with 25" x 15" of screen real estate.
That got me thinking though -- in the old days when websites were commonly 600 pixels wide I used to use opera to browse two sites side by side commonly. Opera allows you to open any combination of tabs side-by-side, kind of like windows within the application but easier to keep track of for me. Now I'm really accustomed to firefox and like some of the extensions, but still I haven't found a side-by-side tab extension for firefox.
So how do people with very wide monitors make use of the screen space? Do you simply open two or three separate instances of firefox manually each time you want the side by side?
Is there some application to open each instance to a separate start page?
Tab sets are great for opening multiple related references at once and to start out with the day's sites each day; is there something similar that would open a group side by side? (1 row x 3 columns or 2 rows x 3 columns)
(Currently using most apps maximized most of the time, when I want smaller windows or with some newer apps that have the palettes float linux-like I find working with smaller windows somewhat inexact and messy in terms of window and palette placements to one another, but maybe I'll adapt quickly and stop adjusting each window one pixel over to be perfectly neat...)