If you setup mod_cluster and use the default configuration/ports used in httpd.conf of 6666 in your initial modcluster configuration, when attempting to browse http://(server ip):6666/mod_cluster_manager from a Chrome browser you get "The webpage is not available". Initially this feels like a 'File Not Found' exception indicating that the mod_cluster module may not actually be setup correctly. On closer investigation you'll see that the actual error is:
Error 312 (net::ERR_UNSAFE_PORT): Unknown error.
There's a workaround is to change the port to another port not marked as 'secured' or do what is described here but this is a hurdle to new users trying to test out their mod_cluster integration with Chrome:
http://superuser.com/questions/188006/how-to-fix-err-unsafe-port-error-on-chrome-when-browsing-to-unsafe-ports

Firefox loads the same page fine.

Either way if it complicates modcluster setup and testing and we can get around it by suggesting a different port(ex. 7777) I think this is preferable. If not we should at a minimum include this as a note in the installation and trouble shooting guide.