Chat

Bombyx
Bombyx is a graphical client for SILC (Secure Internet Live Conferencing). It is written in C++ and uses FLTK as the widget set, plus a few other libraries.
http://bombyx.sourceforge.net/

Chatterbox
Voice chat software, good for online training, seminars, or communities, including text, voice chat, co-browsing and application sharing.
http://www.howudodat.com

Comms4free
Lists only freeware or ad-ware communications software, including text chat, voice chat, and video chat. Descriptions provided.
http://comms4free.webz.cz

Irssi-SILC
Irssi-SILC is the original textmode client for SILC.
http://www.silcnet.org/

Lister Smart
A sleek and useful solution that is set to change the perception of SMS as a communication tool.
http://listersmartsms.tripod.com/ListerSmartSMS/

Milc
A SILC Client for Windows, Linux/*BSD, and Mac OS/X. Has integrated public/private key support, OS standards interface, and HTML rendered output.
http://milc.sourceforge.net/

Stealth Chat
Freeware program that includes strong encryption and stealth measures. Ideal for office workers.
http://www.geocities.com/justnevergo/

Wander
By dragging the address or link in a browser to this software, you can publicly or privately talk to other users reading the same webpage.
http://www.smiletiger.com/