MAC VOICE COMMANDS ROCK.
I used to use them a lot, years ago. I'd have my computer boot up Tomb Raider when i said "Boob raider" and other silliness.
I have arthritis. Lately my wrists have been killing me. I just got around to programming voice commands for all the web pages I regularly browse. Suddenly I'm surfing without touching the computer unless I want to type an actual reply!
The voice recognition has improved. Sometimes it's still a bit flaky about "move page down" and opens Pagespinner for reasons I can't understand, but I just say "quit this application... move page down" and it gets it. So I can move page up/down/to top/to bottom or switch from one application to the next or jump to any page I've bookmarked. I don't have to record my voice, it just figures out what I'm saying. Usually. (It seems to have a better time with words in the dictionary than words like "aulu" where it may be guessing on pronunciation. It gets "Imladris" though.)
Now if only I knew how to tell it "tab-tab-tab-tab-click" so I could skip using the pointer to select items. I'm sure there's a way, I'm just not quite sure what it is.