Identity Impersonation at Code Level

http://www.codedigest.com/CodeDigest/9-Identity-Impersonate-at-Code-Level-in-ASP-Net.aspx

http://crunchlife.com/articles/2008/05/27/temporary-identity-impersonation-in-asp-net

http://chiragrdarji.wordpress.com/2007/03/01/impersonation-using-code/