Everyone wants to know what Apple's Next Big Thing will be. So we gazed into our crystal ball to glimpse these four ripped-from-the-future prototypes of devices that Apple could make in the years ahead. Join us this week as we post a new prototype every day thought up by the Mac|Life staff, and feel free to share your own ideas in the comments.

Apple will refresh its tablet to be flatter than ever--except when it's not flat at all.

The world has caught 3D fever. It’s in our TVs, game consoles, Blu-ray players, and movie theaters. In due time, 3D features will probably even appear in our shampoo and breakfast cereal (”No, Mommy--I want Cap’n Crunch 3D!”). Yet Apple seems conspicuously ambivalent about all the 3D hype. Are Steve’s engineers really treating 3D as a passing fad? Of course not. They’re just going to wait until 2013 in order to do it right.

The iPad 3D’s dimensions will approximate those of the current iPad we know and love. Height and width will be 9.5 inches and 7.5 inches respectively, but the thickness of the tablet will slim down from a half-inch to a shockingly thin one-fifth of an inch. It’s difficult to reach these svelte dimensions under any circumstances, yet Apple will also finagle a 3D display on top of the device’s dainty circuit-board sandwich. And you won’t need cumbersome glasses to enjoy the 3D magic.

1. We'e found that parallax barrier displays tend to excel at showing objects receding into the background, rather than objects jumping out of the screen. So the iPad 3D will come with desktop themes that "embed" unique spatial effects and animations beneath the screen's surface. The theme you see here mimics a swimming pool. Tap the icon of an app you want to load, and animated 3D waves ripple forth.

2. Note the edge-to-edge display—the black border around the screen's perimeter is gone! If you want the border back, just push in the same toggle switch that locks screen orientation in the current iPad. You'll lose some screen real estate (and pixels), but you'll gain a place to put your grubby mitts.

3. The iPad 3D will increase 2D screen resolution from a current spec of 1024x768 to roughly 1280x1024—and, yes, that 2D resolution will engage dynamically when non-3D content is displayed. Because it'll have to split its horizontal pixel grind in half for 3D viewing, the 3D resolution will be an effective grid of roughly 640x768. We write "roughly" because the rounded edges decrease the display's total pixel count. Never heard of an LCD grid that follows a gentle curve? Toshiba Matsushita announced this technology in October 2007.

Don’t scoff. In early 2011, Nintendo will release its 3DS, a handheld gaming system that uses “parallax barrier” technology to render surprisingly effective 3D imaging effects—all without the nerd glasses. We believe that Apple will be implementing an even more mature iteration of this technology, which, like all 3D display systems, uses stereoscopic imaging to create the illusion of depth.

In a typical 3D viewing scenario (say, watching Avatar in the theater), the screen projects two different images—each of the same object or scene but from a slightly different perspective. In the theater, your 3D glasses filter these projections in a way that guarantees one image hits your left eye and the other image hits your right eye. Your brain then synthesizes the two images into a 3D spatial representation. In a parallax barrier scheme—like what you’ll find in the Nintendo 3DS and the iPad 3D—the screen actually aims different sets of pixels to hit one eye or the other. In essence, one pixel set is angled toward your left eye, the other is angled toward your right eye, and a virtual barrier ensures each eye sees the correct set. When the system works, the technology is remarkably effective and no glasses are necessary.

Now, granted, in a parallax barrier system you have to hold the screen at just the right viewing angle and distance from your eyes. But we trust that by 2013, Apple will have a workaround for this dilemma (because, hey, it’s Apple). From gaming apps to HD video content, Apple’s most novel tablet will deliver 3D to your entire mobile entertainment experience.

Say Farewell to "Slide to Unlock"

The iPad 3D’s entire screen will serve as a biometric security reader. Just touch anywhere on the screen, and it’ll scan your fingerprint and wake the device from sleep. Depending on what level of security you define in Settings, the system can grant access to your hands and your hands only. Want your kids to have an open door to some apps but not others—or need a guest account for easier sharing? Simple. The tablet supports multiple user accounts for registered fingerprints with full parental controls, and you can turn on a guest mode that lets anyone access what you define as “safe territory.”