I see your, 'fixed width web content' rant, and raise you a 'running browser full-screen' rant. There's no useful purpose (as you've so elegantly pointed out) to running your browser the entire width of your monitor. In fact, the entire point of a wide screen monitor is so you can get more done (ie, more done at once.) So, have your browser as a nice window on the side, that's in a size and shape that's useful for the content, and use the rest of your widescreen monitor for something else. Save 'full-screen' for those times when the content dictates that you use full-screen.
I find it interesting that 'zooming' was one of your proffered solutions, but scrolling isn't. You realize that even if you did zoom, you'd still have to scroll?