Doesn't make sense from a logistics standpoint, because a render job needs to be finished within a certain timeframe, whereas SETI doesn't really give a damn whether record #968414651165154 gets processed this week or two years down the road. Not to mention how you could be sending your assets to various strangers leading to the data ending up in the wrong hands or simply the sheer amount of data to be sent around (complete scene file and assets in one direction, uncompressed images in the other).
Stuff like this only works in a controlled environment, like FIRE at Foundation Imaging, back in the days of Babylon 5 (before the whole "Netter Digital" thing) and Voyager (when they took over after Amblin Imaging closed its doors, beginning the transition to an all-digital show).
Actually it could work. Not much different than cloud rendering.
Scenario....
Using Blender as an example, and its excellent built in renderer that can be either pure CPU or hybrid GPU/CPU.
Establish a minimum system requirement (doesn't have to be HP Workstation powerful).
Have them download and install Blender.
A typical vfx shot is 7 seconds or shorter. Same if making a fully animated movie.
You divide your rendering into shots, not scenes. Send shot to be rendered to distant computer, have the output uploaded to a central storage area (ie Dropbox or similar).
Bring output in compositer, go from there. You could even have multiple sites for compositing, major studios do that when using indian or chinese render farms.
Yes, it takes time and effort to setup properly, but is doable and most shots, even on a typical desktop computer can be rendered in less than 12 hours. You can even subdivide the shots into different layers to make things even simpler.
There is other free software, like LuxRender that operate as standalone or plug-in to ouput photorealistic images (great for set extension, replacement).
Does anyone know people in their neighborhood who would like to help out? Mainly using the computers overnight.
Important to do a small test render on each machine to ensure output is what you are expecting.