ResLink

Automatic resolution changer for old games.
http://home.online.no/~kr-lund/ResLink.htm

Microsoft DirectX

Libraries that are used by many Windows games.
http://www.microsoft.com/windows/directx/

Roger Wilco

Real-time voice chat for players on a network team.
http://rogerwilco.gamespy.com/

GameRanger

Macintosh multiplayer online gaming service.
http://www.gameranger.com/

Kali

Allows play of IPX games over TCP-IP.
http://www.kali.net/

Alternative Game Server Monitor

A utility for Windows which locates and monitors game servers for many popular LAN and Internet games.
http://www.agsm.net/

Apple Game Sprockets

Extensions for making games both easier to use and to develop thare are required to play many games.
http://developer.apple.com/games/sprockets.html