Voice control can be a very efficient keyboard alternative, but the different
software have different philosophies.
Dragonfly is a
framework that abstracts several speech recognition backends and lets you
program domain specific grammars for voice control. Dragonfly is not an
out-of-the-box solution in itself, but there is another project called Caster, which builds
on it and comes configured with rules and grammars for different domains.
Caster is for people who would like something that focuses on high-level
application and programming language specific phrases, and takes the role
of their text editor and window manager. It works on Linux (X11 only),
Windows and Mac.
Numen is a simple alternative to a
keyboard where you type by saying syllables and literal words. It's for people
who would just like something close to a keyboard so they can use standard
keyboard-focused tools without any integration or switching between phrases.
It works system-wide on Linux.