Update: Dyndns no longer offers our old format for hostnames. Please select a "*.dyndns.org" hostname when requesting a free host, such as:
discoptc.dyndns.org
If you are thinking of hosting a Discovery server, I recommend you look into using a dynamic host name provided by DynDNS.com (http://www.dyndns.com/). Dynamic host names allow you to host a server on a connection with a dynamic IP, allows you to change hosting facilities without redistributing new connection information, and allows you a quick disconnect if you decide to retire your server (so users don't continue to ping your connection even though you stopped hosting a server).
Most of the main discovery servers are using this service and have elected to use .dyndns.org as the domain for our servers.
I try to maintain the list of current servers and submit them for later releases. If you would like your server included in the next release, please PM me here and I'll include it in the submission.