Windows

At the bottom for a reason, but like everyone else it is a necessary evil. Gotta get those hands dirty.

Most useful thing to be able to do is to shut the whole thing down. The keys are <super+R> to bring essentially opens up a single line of the command prompt. Then shutdown -st 0 to immediately turn the computer off. The argument r instead of s is restart and 0 is how many seconds to delay.

ctrl + alt + esc will directly bring up task manager