Windows Key + Power...
On the older TabletPC's there was a CRTL-ALT-Delete Key, but as aesthetics removed more and more buttons the switch to Windows Button and Power became the norm. First utilized on the Samsung Series 7 Slate which became the model for all future Windows Tablets.
Okay, Jeff.
What combinations of power/volume/haptic buttons do you know? Let me pick your brain, 'cause I might as well jot them down on a post-it note and stick it behind my kickstand. I probably won't remember them when I need to.
Or you could carefully etch it in with a compass ...
Windows Key + Power...