Texas Instruments (TI) is working on a miniature color projector suitable for installation in cell phones. In fact, they recently demonstrated something along exactly those lines. When it will hit the market is anyone's guess.
If cell phones have a fault, it's their tiny displays. Efforts to increase display size have focused mainly on...well...on increasing display size--a laudably straightforward approach but one with clear limitations. I mean, at some point, the phone becomes a tablet PC and will no longer fit in its stylish leatherette holster.
TI is showing us a better way...at least, up to a point. If you're not walking around and if you've got a light-colored surface handy and if conditions aren't too bright, you could have a virtual display much larger than your physical phone. And what could you use it for? Less than you probably think. The problem is that it will jump around as you press the keys, so composing email or text messages or even dialing a number is probably out. (And there's nothing like nausea to shut down techno-lust.)
That leaves only two things: Web surfing (in which you spend most of your time reading, not typing, so the bounce isn't as much of a problem) and watching videos. This could be a significant benefit, actually. Web surfing in particular is probably the single most painful cell phone activity there is--so much so that most of us refrain, in fact. Improving it would be a boon to humanity.
The technology (if it makes it out of the lab) could have interesting effects. For example, oral arguments (as, say, in pubs) are often fought on emotion, cleverness and volume--not so much on facts. Wide dissemination of true Web-browsing phones could change that as facts moved literally to people's fingertips (or thumbtips, I guess) whence they could be shown easily to other (and, in crowded conditions, on other) patrons.
The early adopters will have a significant advantage, of course. Imagine stopping a less-well-armed opponent's argument cold with a quick search-and-project. The unequal armaments will lead to plenty of rigged bar bets. With a little preparation, for example, you could easily project a "Wikipedia" page stating in all seriousness that the Fertile Crescent is located in New York City at 28th Street and Lexington Ave. (Note to Americans: it isn't.) If the people on the other side of the bet lacked projectors, they'd pretty much have to pay up.
That's probably just a phase, though. Once it is widely disseminated, the technology should result in more intelligent conversation and better-reasoned debate...not to mention (and when it comes to intellectual stimulation, this benefit is hard to beat) the ability to watch high-resolution episodes of "Gilligan's Island" whenever and wherever we please.