How about a voice activated oscilloscope? For those times when both hands are busy and you really need to hit the ‘single shot’ button. The system doesn’t have to accept many commands so it can be quite accurate with no training and a fair amount of background noise. Open source PC based oscilloscopes such as the CircuitGear give the hardware and platform.
Not sure of the options for speech recognition. A web search for ‘open source speech recognition’ only really gives Sphinx unless you are on Windows and can wrap the Microsoft speech recognition APIs. I used to have a Motorola phone that, after a bit of training, would handle quite a few words. It would take the best match which was entertaining when you’d only trained it on one word.
Great idea — one almost always needs a third hand when using a scope. Let us know how your new software scope goes, or whether you pursue the speech recognition idea.