IBM ViaVoice SDK for Linux  
   The ViaVoice Kit provide the necessary tools to develop applications that incorporate speech recognition using Linux
   http://www-3.ibm.com/software/speech/dev/sdk_linux.html

FreeSpeech - Free Speech Recognition for Linux  
   Openmind (Freespeech) is a free speech recognition project for Linux. It will be designed so that it can be easily integrated into any application or window manager as well as the KDE and Ggnome desktop environments.
   http://freespeech.sourceforge.net/FreeSpeech/html/

Viavoice Mailing List Official Website  
   Archive of messages on the Linux Viavoice mailinglist.
   http://viavoice.sparklist.com/

The Festival Speech Synthesis System  
   Festival is a general multi-lingual speech synthesis system developed at CSTR. It offers a full text to speech system with various APIs, as well an environment for development and research of speech synthesis techniques.
   http://www.cstr.ed.ac.uk/projects/festival/

Unix Speech Recognition  
   Special Synapse TAP Workstation translates speech into mouse events and keystrokes to control all environments - Unix, mainfame, and Mac with speech recognition.
   http://www.unixspeech.com/

Speaker - Text to Speech for Konqueror  
   A text to speech plug in for the KDE desktop file manager under Linux.
   http://dogma.freebsd-uk.eu.org/~grrussel/speaker.html

Bayonne - Telephony Server of the GNU Project  
   Bayonne is the free multi-line telephony server of the GNU project. Source code available for LINUX/UNIX targeted towards messaging, IVR with considerable extensibility. Bayonne supports a modular architecture, native scripting and TGI.
   http://bayonne.sourceforge.net/

CVoiceControl - just say it!  
   Cvoicecontrol is a speech recognition system that allows users to convert spoken commands to Linux/unix commands. For KDE and X windows.
   http://www.kiecza.net/daniel/linux/