mIRC, the most widely used IRC Chat client: 
http://www.mirc.com/

Klient, a good alternative to mIRC:
http://www.klient.com

Trillian, an instant messenger client with IRC support too. Run 1 program for IRC, AIM, ICQ, MSN Messenger, and Yahoo Messenger.
http://www.trillian.cc/

Bullseye Crosshairs has tons of replacement crosshairs for you to choose from.
http://www.bullseyecrosshairs.com/

Firearmsmod is the official website for Firearms
http://www.firearmsmod.com/

FA-Nation has lots more info about the Firearms mod
http://www.fa-nation.net/

GeekPlay allows you to playback demos recorded in any Half-Life mod
http://www.geekboys.org/geekplay/

Cyberathlete Amateur League (CAL)
http://www.caleague.com/

Firearms League (FAL)
http://league.firearmsmod.com/

Stronger Than All (STA)
http://fa.stronger.org/

FA Models - the official site
http://models.firearmsmod.com/

Lunatic Labs - more models
http://www.lunaticlabs.de/

The CLQ regularly polls servers and gathers statistics about players. The results are tallied into rankings.
http://www.theclq.com/

FA Clans
http://clans.firearmsmod.com/