Alternative Game Server Monitor: A utility for Windows which locates and monitors game servers for many popular LAN and Internet games.
asq - Mame Cabinet Front End: A unix curses display for mame/xmame that can select what can be played using mame cabinet controls.
FreeGameCam: Tool for Windows to periodically take screen captures of what you are playing and display the most recent on the web for others to view.
GameRanger: Macintosh multiplayer online gaming service.
GameStat Library: An application and open source library for querying status of game servers.
Kali: Allows play of IPX games over TCP-IP.
Microsoft DirectX: Libraries that are used by many Windows games.
ResLink: Automatic resolution changer for old games.
Roger Wilco: Real-time voice chat for players on a network team.