Have you ever printed out an e-mail message or meeting agenda, only to throw it out a few hours later? If Xerox researchers are to be believed, promiscuous printing happens all the time. Based on studies at their own office and elsewhere, the researchers claim that up to 40 percent of all documents printed in offices are discarded within a day.

The company has a solution: erasable paper. Hailed by Time magazine as one of the best inventions of 2007, the paper is coated with a chemical that changes color when exposed to a certain wavelength of light but fades back to its original shade in 16 to 24 hours, making the paper reusable. Of course it doesn't last forever. Dirt happens. But a Xerox
spokesman says the paper can survive about 50 passes through a
printer.

Erasable paper may save trees but not printers: Xerox research suggests you'll want to have a separate printer for disappearing documents. Send your document to the wrong printer, and you could turn your company's annual report into a daily report.—Dawn Stover

Seeing is believing, check out Xerox's video here.

The world is full of mysteries, and we at Popular Science strive to
do our part to help you make sense of them. What do animals dream about? Is there any way to ensure a blink-free photo? And what is the worst sound on Earth?

Just got this in the personal inbox: an e-mail made to look like it's from the IRS and announcing a small refund, small enough that I nearly believed it and clicked through. But then I tried the old trick of hovering my mouse pointer over the link to reveal the real address. In this case, http://gateway.asoec.com.br/ ~andrea/caseid886432. Definitely not the IRS. Too bad; I could've used $63. Anyway, keep your eye out for IRS phishing scams this time of year. —Mike Haney

There are a couple ways to swap that horrible default chirping noise for something more pleasant without shelling out $3 a tone to your carrier. The easiest way is to use the Web service Mobile 17. Sign up for a free account, enter your phone model and provider, and upload your MP3 or M4A file. Choose the point in the song at which you want the ring to start and how long a clip you’d like.

Talk about a split personality: Xentex Technologies' Flip-Pad Voyager has one huge 20-inch display that splits to serve two masters. Just rotate the right half 180 degrees, attach a keyboard and mouse, and you and a friend can separately surf the Web, read e-mail, or work on a project—or you can play a game head-to-head. If you're computing solo, the two halves complement each other with, say, a Web page on one side and a document on the other. At 12 pounds, it takes the two-laptops-in-one theme too far, but it double-folds into a diminutive 14- by 10- by 3-inch package.

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A few months ago, we showed you the multifunctional Origami Communicator and wondered: Is this where the PDA is heading?