WinSizer

WinSizer will resize the windows of the most known web browsers like Internet Explorer, Mozilla Firefox, Opera or Netscape Navigator, or any other window class. Its purpose is to help web site and software designers, who typically work on a high-resolution screen, to assess their user interfaces as they would appear on smaller screens. Built-in screen sizes include 640x480, 800x600, 1024x768; you can also specify any custom size.
When resizing the windows, WinSizer takes the size and position of the Windows taskbar into account and subtracts that from the requested screen size. This mirrors Microsoft Windows behavior in that it reduces the available desktop area for the window. For example, a typical 800x600 screen setup has actually an available desktop area of 800x572 once the taskbar is subtracted.
Obviously, the available space inside the application window depends on its configuration: which toolbars are visible, whether or not any scrollbars are active, etc. It is up to you to configure the various browsers or applications in a way that reflects your typical audience.