A tool we often use at Graymatter is a very useful Google Labs project, which has been doing the rounds for a few years - Google Labs Browser size. It’s not a massive trade secret, or a work of technical genius, however it is a helpful tool to help the design process.
Basically, the tool overlays an opaque grid over a website/image identifying the percentage of users who use a given browser size dimensions, making it possible to see what percentage of users can see certain parts of the website. However like all average statistics online, these percentages might not be a good representation of the audience for that site; for that reason it is more a starting point.
Whilst testing recently, I thought I would test the Graymatter site after our design refresh.
The main content region is viewable to 90%-100% of users. The calls to actions on the general content templates have also been moved to prominent places at the top of the page. Again in regions viewable by above 90% of users.
Even though we use this as more of a basic guide it is useful to know that the experience for the user on the page might be made better by reducing the need to scroll to find important information, and ensuring that the content we want the majority of users to see is in the most viewable area.