We wrote an extension for Google Chrome which provides a toolbar interface for testing extensions on a page. It looks at the HTTP security headers, enumerating the configured values and provides guidance on the most secure settings. Other things like meta data and form fields with security specific settings are also reported. If you're a developer, or software tester (or security professional) then you might find it a useful addition to your toolbox.
Details here:
http://www.recx.co.uk/products/chromeplugin.php#httpheaderan...
Or search for 'Recx HTTP Header and Cookie Security Analyser'