Well let me see if I can expand the scope of games for you:
Adventure games: e.g. Zelda - Nintendo had a patent for an automatic in game hint system a while back. If you start getting stressed because you can't figure out what to do, the game can automatically give you a hint to get you back on the right track.
Horror game: e.g. RE/SH - Vitality sensor picks up on your level of panic and increases/decreases the amount of pop-up scares or number of zombie/monsters coming after you until you reach an optimum level. Maybe light the pathway to take or highlight an important object you need to help you stay alive or just progress
Music/Rhythm game: e.g. GH/RB - it can change the level of difficulty by speeding/slowing down the song or how many notes needs to be hit to keep up. Maybe intensify the background visuals if are breezing through or tone it down if your panicking. Maybe even change up the next song to something a little more difficult or a lil easier.
Driving game: e.g. MK/NFS - Increase/decrease the number of drivers attacking depending on your heart rate or whatever else it sensing. Change your track order to help you not get too stressed or ramp up your level of excitement.
Puzzle games: There was supposedly a Tetris game back in the day that used some tech like this. I guess it would in/decrease the number and/or speed of falling blocks depending on your level of panic, imagine something like that for all the other puzzle games you can think of. Or if you not stressing on a puzzle, maybe a timer pops up to make you sweat a little.
Those are just a few possibilities off the top of my head. I'm sure you guys can come up with some more.
Of course it still comes down to 3rd parties trying to do new stuff outside of the comfortable safe zone which we consider "thinking in the box". Think of something like a new Trauma Center that also measures your heart rate while you play, a Tetris, Silent Hill, BoomBlox, PunchOut, Mario Kart, and how little changes in what the sensor picks up can change the game to in/decrease the difficulty or the ambiance of the surroundings, the volume or intensity of the music/sfx.
WiiFit Health Pack+ can't be all you can imagine with this sensor. But don't get me wrong, I'm not betting on this sensor just yet. I'm still curious how you are gonna wear that thing and play most of the games I suggested. Its a little bulky to wear while holding the Wiimote and what happens if I also have the nunchuck plugged in... then what. I'm still waiting to see exactly what Nintendo has planned, but that doesn't mean we can't imagine whats possible before they do.
So discuss.