Cameras With Time-Machine Powers
nytimes.com
nytimes.com
I click the program icon (or hit a hotkey) and poof it saves away the current bucket of images with a name of my choosing.
Maybe I'll see how possible it is to make a skimpy little tool that does this, as it would help me a lot in debugging and remembering things that just vanished.
But I would buy it.
My answer - 'wasteful' things like this. Useful, but only if you have plenty of spare capacity to run them in.
Maybe that's only because in my head, time machines let you travel to another point in time rather than move slowly through time.
(I imagine that an actual time travel camera is doable. It's just an always running video camera that saves off the last N seconds when you press the button.)