Something that I would find much more useful is a button that cycles through all the 'Closed Captioning' activation codes.
So many TVs in public have the volume low (which is good) but have closed captioning turned off (which is bad). There's no way to actually get coherent information from most programming this way. If you're in a loud bar or restaurant, having the volume up would be intrusive for those who choose not to watch TV. But if you activate the closed captioning, then anyone who chooses to watch will at least be able to understand what they're seeing instead of just watching the 'pretty pictures'.
I'm reminded of the slashdot poster who, on the day the sample return capsule crashed without deploying a parachute, turned on the TV with the sound off and the saw what appeared to be a flying saucer half buried in the desert with the words 'BREAKING NEWS' flashing across the bottom.