Simple Explanation and usage

http://www.dotnetspider.com/resources/260-ASHX-Files.aspx

Microsoft Knowledge Base Article on ASHX

http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q307985

A Low level guide to the ASP.NET Pipeline

http://www.code-magazine.com/Article.aspx?quickid=0511061

A sample album photo ASHX file

http://dotnetslackers.com/DataSet/re-11735_Sample_album_ashx_handler.aspx