GameSpy Arcade!

GameRanger is a free download for Mac and PC that lets you play over 600 games and demos online with friends and opponents worldwide. GameRanger offers features like profiles, friends lists, instant messaging, in-game voice communication, and competitive ladders/rankings/ratings.

GameTracker is your one-stop social network for gamers with game server stats, website plugins, and game server banners. From current scores to historical player data and worldwide game server ranking, Game Tracker records detailed statistics on how you, your clan, and your gameserver fare against the competition.Windows and Mac OS users can download GT Lite Client.

Garena is a free downloadable software provided by Ocean Global Holding. Garena, short for Global Arena, is a multifunction platform that allows gamers to chat, challenge opponents, and play their favorite games online with millions of gamers world-wide.

A direct "like for like" replacement for the GameSpy MasterServer, and supports a huge number of games.333networks is the official MasterServer for several games companies, and can be self-hosted, or use the main Master, or both.