CodeSnip: How to Select Record(s) Using Checkboxes and Delete on Confirmation in GridView
http://aspalliance.com/1014_CodeSnip_How_to_Select_Records_Using_Checkboxes_and_Delete_on_Confirmation_in_GridView#Page4

Selecting, Confirming & Deleting Multiple Checkbox Items In A DataGrid/GridView - Part 2: Maintaining CheckBox State Acr - Our Main Page
http://www.developerfusion.co.uk/show/5258/2/

Multi-select ASP.NET datagrid （中文）
http://www.cnblogs.com/rippleyong/archive/2004/12/15/77563.aspx