OverServer
Simple meta-server for locating other multiplayer servers
...The OverServer is an open-source tool for game developers who are working on network games and do not require a massively scalable backend for their network services but want a metaserver for their own games.
One particular strength of the player-hosted games setup is that it places the burden of Internet traffic on the player base and not a central server. OverServer tries not to violate this strength by keeping the query and response length very low to cut down on overhead from running the metaserver.
I designed OverServer with a few lessons in mind from Valve and Won's metaserver setup for Half-life. ...