This tool is a nice quick check for what a page looks like on a continuum of screen resolutions.
Using it has reminded me of two things:
1) How important top-left is.
2) How great gear can lead to blindness. I never have to scroll on my octo-monitor, pixels-forever, V8-powered display system. Suddenly, a beleaguered middle-aged bureaucrat bursts in. Sir! The peasants are scrolling! Ha, says the soon-to-be-hanged aristocrat, let them run dualies!