Whether you're debugging web application issues, or performing forensics on web logs, this iPhone/iPod application provides a handy reference to all Hypertext Transfer Protocol Status codes. It contains descriptions to all Client and Server status response codes - e.g. 404 is a server response code which means that the requested page was not found.

Future updates could include popular http headers, or user agent descriptions - it's up to you, send feedback to http.codes@gmail.com.