When choosing what to eat, there are usually tradeoffs between taste and nutrition.
Good nutrition: water, beans, fresh fruits, whole grain foods.
Bad nutrition: soda, beef, cheese, salt, chocolate.
Why do I have to make those choice? Why can't I have nutritious chocolate? The problem is that after many millions of years of evolution, primates prefer food that lets them fatten themselves up, because they're more likely to survive through famines. And evolution only weeds out bad habits that kill you when you're young. So we ended up liking foods that will kill us in the long run. But this is a solvable problem.
I'm starting to notice more things in the world where there are two options, and both of them are unpleasant (e.g., either you have heart disease or you give up fatty foods). In cars, either you give up gas mileage or you give up horsepower. For energy, you either give up comfort (air conditioning, etc.) or you hurt the environment. With programming, you either have slow reusable code or you have fast messy code. For cameras, you have high resolution still pictures or low resolution movies. I don't want to make the tradeoff anymore. I want the best of both.
With food, let's decouple nutrition and taste. The simplest (but perhaps ugly) way to do this would be to divert food after it has hit the mouth (where it contributes to taste) but before it hits the stomach (where it contributes to nutrition). We could then feed supplements into your stomach.
Since the supplements are much smaller than real food and they don't need as much digestion, we can downsize the stomach and intestines and maybe some other organs. You could use that space to keep all the diverted food. You could use any additional for storage, like Bender on Futurama.
Every once in a while you'd have to remove the supplement cartridge and plug in a new one. Unfortunately Lexmark will use DRM to prevent you from refilling your nutritional supplement cartridge.
That way I could eat all the unhealthy food I want and it won't impact my health. No tradeoffs, other than the Lexmark issue. Don't settle for less.
Car sun shades are very useful. You can put them up when you leave your car to keep the sun out. This keeps your car cooler, reduces the amount of gas you use slightly (because you don't need to run your air conditioner so much to undo the heating), and helps protect your seats and dashboard.
The problem is that they are manually operated. The popular silver shades are unrolled and placed in the windshield. There are also black perforated shades that can be pulled out. They're manually operated because it's too expensive for third parties to automate this stuff into every type of car.
Carmakers should automate sun shades. When the car is off, you should be able push a button to have a sunshade come up. For the windshield it could be set up just like the windshield wiper—an arm comes up and spreads out a folding shade. For the side windows it could be like the power windows—a reflective cover comes up from the door. Someday we'll use windows that can become opaque. Right now it's too expensive, but maybe in five years it will be reasonable.
If we had automated sun shades, far more people would use them.
Update: [2006-07-30] These car shades are a step in the right direction.