Video showcasing ISO noise behavior of a few different cameras: https://youtu.be/iiMfAmWbWSg?t=94s

That's a pretty good demo!

Very limited camera choices, though.

Yeah, it would be interesting and useful to see this across many more cameras.

dpreview is good for that. They shoot a test image of every camera on the market, and you can compare specific iso values on the same subject side by side.

Some of the new Nikon cameras have excellent high-ISO performance. Also, they now own RED, so we should see some interesting stuff, down the road.