Thor is Internet Explorer driven tool for manual web application testing. Both security professionals and testers found it useful while testing web applications.
You can control (intercept and change) what web forms submit to web servers, see the source code of the page and/or manipulate cookies. It supports frames and, if required, it is possible to use HttpWebRequest instead of IE navigation.
Built for .NET Framework 2.0 and, as it uses IE COM control, it requires FullTrust.
Sorry, no proper web page or manual yet, but give me a shout if you need more information...