Create a Site Search Engine in ASP.NET
Another good stuff found in Developer Fusion, great site by the way.
This time written by Stevan Rodrigues and to show how to build a Search engine in your .Net project.
Introduction
The Search Engine module will search an entire page also dynamic pages for matching keyword(s) or a phrase and will count how many times the keyword(s) or phrase are found on the page, and display the results with the highest matches first. The module will search all files with the extensions that you can easily place the extension name into the web.config file where indicated. Files or folders that you don't want searched can be placed in the web.config where indicated, so these files and folders are not searched.