I have used the comment stripping plugin, originally developed by Kenneth Crowder, for years. The extension was written for Joomla 1.5. I found this extension SO invaluable, that I decided to port it over for use in Joomla 1.7. I hope I did the original developer proud! If you have any issues with the plugin, feel free to contact me. I am NOT a professional developer, simply an avid user who loves this great little extension!
For a direct download of the extension, CLICK HERE.