HLSW or Half-Life ServerWatch is an awesome administration tool to manage your game server. It's primarily a tool for admins, but regular players can use it too (as a server browser). With HLSW you can chat to players on your server without ever entering the server! You can execute RCON commands, change the map, etc.
HLSW supports many games aside from Half-Life 1 and Half Life 2. Some of the more popular ones are; Battlefield 2, Call of Duty (all games), Crysis, Neverwinter Nights and more. You can see the complete list at http://hlsw.org/hlsw/supported_games/. HLSW is freeware and compatible with Windows 2000 SP4, XP and Vista.