BitlBee allows users to talk to people on the major instant messaging and microblogging networks (including MSN, Google Talk, AIM, and Twitter) from within any IRC client by emulating an IRC server. Virtual channels are created with all of the user's contacts in them, who can be talked to in the channel or in a query. Also, one can participate in group chats and chat rooms like they were normal IRC channels.
YSM (You Sick Me) v7 is an ICQ console client. It was originally meant to run in Linux, but it has been successfully tested in Linux, BSD, Win32, BeOS, and QNX. The client requires no extra libraries, and is written in the C language. YSM is based on the last ICQ protocol version, v7/8.
Bicq is an attempt to bring connection to ICQ services to the popular BitchX IRC client. It uses BitchX's built-in plugin system to allow users to connect to and chat on the ICQ system as well as the IRC networks. It runs entirely inside the BitchX application, and uses that application's standard interface with its provided commands.
JabberTools is a set of console and Web-based Perl tools depending on Net::Jabber that makes it easier to use Jabber and convert to using Jabber from other instant messaging systems (e.g., AOL and ICQ). The tools include a Jabber account manager and an importer that converts your previous contact lists/rosters/buddy lists into your Jabber roster.
SMSTerm is an application that uses the ICQ2000 protocol to present you a shell on your mobile phone which allows you to interact with your computer from any mobile on a GSM network. It runs a shell on a pty, and allows you to directly send commands to the shell through SMS. Minimal authentication is done over SMS before spawning a shell and offering it to the user on the mobile phone. It is very useful for remote administration tasks, or checking out the status of the network, or just to run some small chores on your system while you are away. It uses Expect.pm in the background. SMSTerm also includes a script to send SMS through the ICQ network from the command line to any GSM mobile, and also includes a PHP script to set up a Web->SMS gateway.