Sensory Inc. Manufacturer of low-cost speech recognition and playback IC's designed for consumer products.
Open source (freeware) speech recognition software is available from the Sphinx Group at Carnegie Mellon University. This software was funded by DARPA, the Defense Advanced Research Projects Agency. From the CMU Sphinx web page, " . . . CMU Sphinx Group is releasing a set of reasonably mature, world-class speech components that provide a basic level of technology to anyone interested in creating speech-using applications without the once-prohibitive initial investment cost in research and development; the same components are open to peer review by all researchers in the field, and are used for linguistic research as well."
Low Cost Voice recognition Excellent article from Circuit Cellar on embedded low-cost (less than $5) voice recognition. Uses a stand-alone microcontroller. See this zip file for the source code you'll need. From the article, "For embedded systems, Tiny Voice can be controlled over a parallel or serial protocol from a host microcontroller or it can run stand-alone. The source code may be modified to fit your requirements. At under $5, Tiny Voice won�t do dictation. But, it�s good for applications like toys, repertory phone dialers, voice-activated padlocks, security systems, remote controls, and other low-cost consumer products."