Kalikops Headquarters - Multi-mod servers for Hunted, Day of Defeat, and Counter-Strike. With files, maps, IRC servers, pictures, and message boards. - http://www.kalikops.org/
UK Deathmatch Classic community - Dedicated Half-Life Deathmatch Classic servers. Site features live players stats, map downloads and forums. - http://www.zapper.org.uk
Free Fall - Half-Life deathmatch classic servers with custom maps, sounds, models, plus regular and low grav servers. - http://www.free-fall.net/
Joe.to Servers - Includes several servers for Counter-Strike and Natural Selection, with news, forums, atciles, maps, and links. - http://www.joe.to/
AlphaSpy - Free tool which allows monitoring of Half-Life or Half-Life mod servers on the net and quickly see vital statistics about the server. - http://users.bigpond.net.au/beredon/alphaspy/
Bob the Server - Dedicated Half-Life server. - http://www.bobtheserver.com/