[Cleo]

I never surf at full screen and don't know too many people that do. Plus some browsers put side bars and other stuff using up the browser's window.

In answer to your question,
Wusage, IMO the very best server stats program, does this if you add a bit of code to your pages.

1. Copy the provided file wusage_screen_properties.gif to the top directory of your web server's web space. This file was provided with Wusage. If you cannot locate it, check the Wusage home page, or use any image you like. The important thing is that you place it in the top directory of your web space and give it the correct filename.
The provided wusage_screen_properties.gif image is a 1x1 pixel transparent GIF. It has no visible effect on the web page in which it is installed to collect information.

2. Embed it in your home page, or another heavily-accessed page, using EXACTLY THE FOLLOWING HTML:
<script>
<!--
        var bName = navigator.appName;
        var bVer = parseInt(navigator.appVersion);
        var ver;
        if (bName == "Netscape" && bVer >= 4) {
                ver = 4;
        } else if (bName == "Microsoft Internet Explorer" && bVer >= 4) {
                ver = 4;
        } else {
                ver = 0;
        }
        if (ver >= 4) {
                document.write('<img src="/wusage_screen_properties.gif?' +
                        'width=' + screen.width + '&' +
                        'height=' + screen.height + '&' +
                        'depth=' + screen.colorDepth + '">');   
                document.writeln();
        }
// -->
</script>
Experienced users may of course modify this Javascript, carefully. The critical thing is that the image be loaded at the URL shown, with the appropriate parameters packed in the format shown. Wusage 8.0 must see the URL as shown above in order to capture the information correctly.