Utilities

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/

asq - Mame Cabinet Front End
A unix curses display for mame/xmame that can select what can be played using mame cabinet controls.
http://marginalhacks.com/Hacks/asq/

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.
http://www.freegamecam.com/

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

GameStat Library
An application and open source library for querying status of game servers.
http://dev.int64.org/gamestat.html

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

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

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

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