Inventions I want to see

Driving home tonight, I listened to NPR and heard that someone has invented astroturf with fiber optic strands embedded so that now commercials can actually be shown on the field during breaks in football games.

I don't watch football, so I don't know how necessary a technology this is (I'm guessing "not at all" would be the category), but here are some inventions that need to be looked into by those who do such things. (Yes, I'm mostly kidding, but wouldn't some of these be useful?)

In addition to searching the catalogue for books, a lot of people like to browse through the stacks looking for books in their field. Since I don't always catch them when they're on the New Books bookshelf, I browse for new books in my field when I'm up in the stacks, but that involves a lot of close looking at the labels.

Wouldn't it be great if someone invented some kind of label highlighter or ink that would change color with the year? For example, new books each year would have the year on the Library of Congress code highlighted in, say, green, which would degrade slowly over the year to a different color--maybe yellow--and then on to brown, until after the 3rd year they'd just be regular white labels. There wouldn't be a new color for each year; they'd just have to invent one kind of ink that would do this and use it to highlight the year on the label (or maybe the entire label).

I also would like some kind of RFID technology that would allow you to wave your library card/university ID at a sensor and just pass through the gate with your backpack or bag of books, so you wouldn't have to unpack the entire load of books from your bag to check them out and then pack them up again.

If you drive regularly on two-lane roads that curve up and down hills, as I do, you know that sometimes it's impossible to tell right away whether an oncoming car is passing the car in front of it or whether the curve of the road just makes it appear that way. If roads had sensors that would make a car's lights blink when that center line was crossed (something that'll never happen), it'd be easier to tell whether you needed to dive for the shoulder or not.

Of course there are fantasy inventions--the keys that shout "I'm right here, stupid!" when I'm looking for them, or the illuminated signs for cars that would say "Back off, fool! Tailgating won't make me go any faster, not in this fog"--but they're pretty ridiculous. I really would like to see the label thing, though.

What inventions would you like to see?