XVoice provides voice control of X applications using IBM's ViaVoice for Linux (free download at their web site). Both user-defined commands and dictation are supported. It can be used to write letters, write code, control netscape, etc.
xvoice version 0.9.5 has been released. RPM's and tarball are available in the file release section. This release should work for KDE users. It also has a somewhat more robust build, and some new dictation features.