AOL Instant Messenger
Addons, Away Messages, Buddy Icons, Aim Dude, AIM Juncture.com, Aim News, Aim Sites, Aim Stuff, AIMFilez.com, AimKaos, AIMMachine.com Offline Messaging, AOL Instant Messenger, AOL's FTP Download
ICQ
FAQs, Help, and Tutorials, Skins, Tools, User Lists, ICQ, ICQ Connection, ICQ Help Page, ICQ Start4all, Old Versions
Jabber
Adium X, Akeni, Amessage Jabber services, Austrian Jabber Services, BuddySpace, CenterICQ, Chatopus for Palm OS, Coccinella, Edgar Jabber Bot, ejabberd
MSN Messenger
Skins, Block Checker, ENat for MSN Messenger, gtmess Messenger - MSN Messenger client for Linux , Heavy K's Hideout, Mess with MSN Messenger, Messenger History, Messenger Plus! Extension, Microsoft Portrait, Mister-i Messenger, Msg++
Away Messages
Suggestions for away messages to use with instant messaging clients.
Jephyr Instant Messaging System
Protocol specification for client-server instant messaging with a Java implementation.
OnlineCall
Instant messaging service that supports video and voice conversations.
PresenceWorks
Tool for integrating instant messaging client capabilities into business software.