The latest incarnation of my open-source ASP.NET no-database-required C# search engine has been updated: Searcharoo version 7 (and on CodeProject)!
It's not a significant release in terms of functionality (just adds proper document excerpt/term highlighting to the results), but it was quite a bit of work to make that happen.
Plus I added some new 'toys': a JSON-formatted result page and two rich-clients that use it (jQuery/AJAX and Silverlight 2.0).
You can play with the jQuery and Silverlight examples online (try searching for parse, search, row, sydney, manhattan or pumpkin)
This will be the last .NET 2.0 version of Searcharoo - future versions will be in .NET 3.5, looking to take advantage of Linq and maybe even Azure...
p.s. You can read about all the previous versions (since 2004) on CodeProject: versions 1 2 3 4 5 and 6.