...on a widescreen laptop. Nearly all websites are made to fit a 1024px width screen, so any extra pixels is just wasted space if you maximize your browser. Also, if a website uses a left-justified layout (like Google search results or craigslist), it's awkward reading content on the far left side.

I normally keep my browser in a window and move it to the right edge. It's the perfect position, and left-justified websites appear in the middle of my screen.