Paligo is an end-to-end Component Content Management System (CCMS) solution for technical documentation, policies and procedures, knowledge management, and more.
qGTalk is a Google Talk client developed with Qt and libgloox. qGTalk functions like the Windows version of Google Talk (currently only text messaging is implemented) but runs on Linux.
VoiceChatter is a free, open source, and cross platform voice chat application. It is built for gaming, so it is light weight, yet delivers excellent voice quality over minimal bandwidth and latency. For more, visit http://www.voicechatter.net