savIRC is an IRC client for Linux, Unix, BSD, and Windows. It supports multiple server connections, SOCKS5 proxy, CTCP, DCC, passive DCC, ignore and notify lists, Unicode, mIRC colors, MDI dedicated windows, logs, customizable popups, pre-defined events, scripting in Tcl/Tk, captions for URL nicks, and channel names.
OpenVerse is similar to other graphical chat systems like Excite Chat and Microsoft Chat, with the main differences being that OpenVerse is open source software, has no advertisements, and also runs on a variety of systems including Windows, Unix, Macintosh, and just about anything else for which you can find a copy of TCL/TK.
NetPlug is an extensible multi-connections, multi-protocol, network client program, written in pure Tcl/Tk. Includes a complete Irc client plug in that you should love if you like IrcII 'classic' look & feel (plus customizable style/colors scheme, sound,... Now includes full DCC support (with GUI), ircII like aliases and improved scripting (Tcl!), keywords (your nick...) highlighting, and more
Cell Messenger is a program that sends, receives, and archives SMS messages from your mobile phone. It provides support for reading your mobile's phonebook, sending group messages, anti-spam SMS filtering, Unicode, and multipart SMS messages. It's also capable of reading a GSM phonebook into its own contact list.
Funpidgin is a modified version of the Pidgin instant messenger application. It was made in response to the controversial auto-resizing textbox that was implemented in Pidgin. Current features of Funpidgin include manual resizing and the ability to turn off persistent window placement. Funpidgin's releases are meant to coincide with Pidgin's releases.