Gurpreet Singh who is a developer in my team published last week a couple of articles on how to extend IIS Manager 7:

1) The first one talks about how to write an IIS Manager extension in general and walks you through the process using Visual Studio: http://learn.iis.net/page.aspx/441/understanding-ui-extension-authoring/

2) The second one shows how to extend the IIS Reports feature in Admin Pack to add your own report to it and shows this using Log Parser: http://learn.iis.net/page.aspx/464/walkthrough-for-creating-an-iis-report/