centericq is a text mode menu- and window-driven IM interface that supports the ICQ2000, Yahoo!, AIM, IRC, MSN, Gadu-Gadu, and Jabber protocols. It allows you to send, receive, and forward messages, URLs, SMSes (both through the ICQ server and email gateways supported by Mirabilis), contacts, and email express messages, and it has many other useful features. An internal RSS reader and a LiveJournal client are also provided.
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.
Pedbot is an AOL Instant Messenger robot that features Eliza mode, area code lookup, calculator, dictionary, Google search/spell, IP mapper, password generator, pickup line generator, random quote, random fact, stock quotes, weather, zip to zip distance, and more. Administrative features include wrappers for: ping, nmap, traceroute, dig, whois, w, host, the ability to set configuration hash values through messaging, and initiating conversations with others, manual block / warn commands, and more.
daim is an IM client and library that supports many features, including add-ins, AIM proxy, buddy icons, chat, direct IM, file transfer, file sharing, send buddy list, and Trillian secureIM. It also supports retrieving News and Stocks, and scripting through Apache BSF. It also supports ICQ, can emulate Apple's iChat client, and supports iChat available messages as well.