[jbaber]

In Linux, I switch to a vty (ctrl-alt-f4) and don't log into it when I want to disable the keyboard.

[yjftsjthsd-h]

I would think in most cases some sort of lock would be fine - whether that's switching to a getty, calling xscreensaver/gnome-screensaver/whatever, or whatever your platform's equivalent is.

[imp0cat]

This. I just lock the machine and have a go at it.