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's laptops will lose the power cord and go even greener.

Think of the MacBook Eco as a hybrid car you can toss in your backpack. Just as a Prius is powered by a combination of gasoline and electricity, the MacBook Eco will stay running with a mashup of technologies that includes solar energy, piezoelectric power, and wireless electricity.

First off, its black coating isn’t just for aesthetics. That’s solar paint, a multilayered mixture of nano-sized dye-sensitive cells and titanium dioxide that can coat any material, going on like paint and drying as tiny—think microscopic—solar cells. Even in 2010, it can harness more of the sun’s energy (up to 40 percent) than traditional photovoltaic cells (closer to 18 percent). That performance also comes at a lower cost, according to NextGen Solar, the startup bringing this technology to market. You can’t just waltz down to Lowe’s and pick up a gallon today, but imagine what could happen if a huge buyer like Apple got on board. Plus, since this paint works on so many surfaces—even windows—Apple won’t have to restrict its creative industrial design.

Of course, computer use usually happens indoors, so solar probably won’t be enough for anyone except maybe Tarzan. But the highly portable MacBook Eco will also use kinetic energy harvested by your footsteps, courtesy of piezoelectric pads on the bottom of a pair of Nike Piezo cross-trainers.

1. Hit a function key for an at-a-glance look at where your power is coming from—the solar-paint coating, the Nike Piezo shoes, or the piezoelectrics embedded under the keyboard.

2. "Solar paint" sounds made up, we know, but it actually exists and is even more efficient than traditional solar panels.

3. No wires? Of course not—this is the future, after all. Electricity generated by the shoes is sent via radio frequency to the laptop. Wirelessly.

4. Since Apple's already partnered with Nike for the Nike + iPod fitness products, they're natural partners for the energy-harvesting Nike Piezo shoes.

5. TYPE HARD BECAUSE YOUR KEYSTROKES ALSO PRODUCE ELECTRICITY. PIEZOELECTRICS ARE AWESOME!!!1!

Piezoelectric technology exists today too. Piezoelectric floor tiles in Tokyo Station and Shibuya Station in Japan collect energy from the footfalls of nearly 3 million people daily, where it’s stored in capacitors and used to power the lights and ticket gates. And researchers at MIT, Princeton, and Louisiana Tech have been experimenting with adding flexible piezoelectric materials into shoes.

If “footpower” makes you think “hamster wheel,” rest assured this is far more science-y than that. Basically—and this is highly simplified—the piezoelectric element is made up of an asymmetrical array of cells of crystalline substances. In our case, this takes the form of a foil layer in the sole of the shoe, as well as a thicker pad in the heel. When hit by an external force—your heel striking the ground or the sole bending during a footstep—those cells realign themselves in a regular pattern, which develops electrostatic potential. So far, the output is roughly on par with a lithium coin-cell battery, but by the Eco’s debut, it’ll have taken great strides—pun totally intended.

To keep the electrons flowing, the Eco also has a piezoelectric layer underneath the keyboard to capture the energy of every keystroke you make. So go ahead and type hard, angry emails—you’re saving the Earth with every Caps Lock rant.

And don’t worry about an ugly 20th-century wire tethering your shoes to your Mac. The Eco will use wireless charging, which will beam the power harvested in your shoes up to your MacBook by converting the electricity to radio waves and transmitting them by RF. A handy graph on the screen shows you at a glance how much of your juice is coming from each source, letting you combine technologies to keep your hybrid MacBook Eco cruising down the information superhighway.