Nested Grid View is useful to show parent child relationship table. This blog post contains example to build Nested Grid View with Asp.Net.
The Parent Grid View content can be Edited and its Child Grid View loads on the fly if user clicks on parent grid view row.
I use Northwind Sample Database to produce nested Grid View. Also I use DropDownList, TextBox with Ajax PopUp and TextBox with Ajax Calendar to filter database query.
I already have example about Ajax Popup & Calendar in this Url Making Flexible User Input With Asp.Net Ajax PopUp & Calendar Extender Toolkit Controls .
So this blog contains miscelanous example. This might be useful for web internal application that contains complex user input & data layout.