No membership required. To quickly join, go to the top download tab and select "e-WarZone client."
The WarZone is a gaming lobby for playing multiplayer versions of older DirectPlay 7 or earlier games. While similiar in concept to GameSpy and the old, now defunct MSN Gaming Zone, it specializes in older games, is completely free and contains no adware or spyware. Moreover, it includes the DirectPlay Router Bypass feature, allowing games to be played without disabling firewalls, changing router settings, or exposing your IP address to other players.
If you're new to e-WarZone, why not register?
The WZ has dedicated, active lobbies for several games and an Open Lobby for all DirectPlay 7 or earlier games.