On any console, the Black Out button. I've never had any reason to use it, but I looooove knowing that it's there. You want to mess with me? I can put you ALL in the dark! And you know my hand's hovering over it during any and all mega-mixes...
I would have to agree with the person who said the black out button. I like the black out button, it is my friend. However, every once in a while I look at it and I think, has anyone disabled this button? Maybe I should check... in the middle of a gig. Though I have been tempted I never have.
I really do enjoy the hold and back button on the ETCconsole at my old high school. It's saved the lives of a few of my MEs and even myself once or twice.
You know what... I like all the button equally..... except for the trackbutton on the etc. I hate that button with a passion and prefer never to use it. Rawr trackbutton... rawr.
Right on with the Black Out button Although I have used it before, for dance recitals, black outs at the end of dances, fade in when next one starts. Besides that, nothing really : P
The ETCExpress/ion [Hold] button has served me well, both for accidental 'GO' presses and for when you need to pause a running cue for any reason. I was running a dance show which was very complicated and after next to no rehearsal time, having one finger near the 'Hold' button while running a cue was very useful ("Does the blackout go on this beat, or the beat after that?").