Essentially, an engaged interface for query building that may be designed to connect with a custom query builder around the after sales (during my situation, MySQL, however it need not be database specific).
I have looked around, and haven't found anything useful or functional.
ExtJS includes a Query Builder extension for their Power grid control: http://www.developerextensions.com/index.php/extjs-grid-query-builder (search for the hyperlink over the table that states Query Builder).
I additionally found this, "Active Query Builder": http://aspquerybuilder.net/default.aspx The feature list is : http://www.activequerybuilder.com/featurematrix.html?show=asp . This is an compensated ASP.Internet ingredient that uses jQuery. It's pretty robust and might be a lot more than you're searching for as well as might be suitable for your framework (you did not specify), however it does look pretty awesome.
More ASP.Internet-based query contractors are linked from : Web based visual query builder.