Unless you've been living off the grid for a decade, you've probably heard of the "Internet of Things" by now. Sites like Barron's have hailed it as "The Next Industrial Revolution." And Wired says we can't even fathom how transformational the Internet of things (IoT) will ultimately be. It's just too early.

But if it's hard to extrapolate how far this technology will reach, it's a little easier to see the specific applications that could be revolutionary in just a few years. We recently asked three Motley Fool contributors to identify the most exciting applications that have crossed their radar screen. Read on to see which ones they think hold the most promise for companies – and potentially for your portfolio.

Source: Nest

Joe Tenebruso (Nest): The technology powering Google's (NASDAQ:GOOG) Nest products is some of the most impressive I've seen in the IoT space, and it positions Google to profit from the major trend toward home automation. 

The smart/connected home was a big focus at this year's annual International Consumer Electronics Show, so much so that some analysts are predicting that 2015 will be an inflection point in regards to Internet of Things technology.

Yet many investors may still be struggling to understand just how pervasive IoT technology can become; research firm Gartner estimates that an average home could remotely connect up to 500 "things," such as your HVAC system, door locks, and appliances. With Nest, Google has acquired a beachhead in its battle to position itself as a control center in this ultra-connected environment. That's a powerful and potentially lucrative position to be in, especially for a company like Google that can use the data collected from all of these connected devices to further strengthen its already dominant ad-targeting machine.

Nest technology also positions Google well within the trend toward greater energy efficiency, with the Nest "learning" thermostat helping customers manage half their homes' energy usage and save up to 20% on their heating and cooling bills.

In addition, the Nest smoke and carbon monoxide detector -- along with Nest's recent acquisition of Wi-Fi webcam maker Dropcam -- gives Google access to the home safety market. I believe Google could eventually expand into the home security space with Nest-controlled door and window sensors, as well as alarm monitoring, bolstering Google's burgeoning ecosystem within home automation.

All told, Google's $3.2 billion acquisition of Nest gives it an early leadership position within the fast-growing and potentially massive Internet of Things market – a position I expect Google to aggressively reinforce in the years ahead. And as the world continues to move toward greater connectivity, safety, and convenience, Google -- and its shareholders -- stand to profit handsomely.

Isaac Pino (Industrial Internet): For investors, I think the most exciting IoT technology will be what's widely known as the "industrial Internet." It's a combination of software and sensors that enable machines to communicate with one another instantaneously. When machines like a railroad locomotive can communicate, they can autonomously conduct repairs or updates and thereby optimize performance. This reduces downtime and increases productivity in a manufacturing sector that represents 13% of America's gross domestic product.

That's a large slice of the economic pie. And, as pointed out by my colleague Morgan Housel, a boost in productivity is one of only two drivers of real economic expansion (the other is an increase in population).

So, on a broad scale, it's the industrial Internet that could boost corporate profits, and these gains will percolate across the entire economy. According to General Electric (NYSE:GE), a leading developer in this space, the various applications of the industrial Internet could add eye-watering $10 trillion to $15 trillion to global GDP in the next 20 years.

GE is already applying industrial Internet software to wind power through a service called Predictivity. Source: GE

As a result, investors of all stripes will benefit from this new wave of technology, either indirectly through economic expansion or directly by picking key stocks in this field. And for those interested in specific companies, two in particular stand out in my book: the aforementioned GE and the Dow chipmaker Intel (NASDAQ:INTC).

Both GE and Intel have been instrumental in developing common standards and architectures through the Industrial Internet Consortium (IIC), and both have a track record of applying new technology in ways that are more functional, and less gimmicky.

Ultimately, it's true that the IoT could transform your home, your appliances, even your car, but I expect a more near-term impact will be felt outside of the consumer market. Narrowing your search to industrial Internet plays will prove a smarter move over the next decade, and GE and Intel are two established names that continue to push the envelope in this arena.

Alex Planes (Self-Driving Cars): Software has a proven ability to improve the efficiency of almost anything it touches, especially when it helps connect disparate operations into a cohesive entity. We've seen this happen across a wide range of industries, and it continues to take shape in new places every day. But one of the greatest changes is still ahead, and it's only approaching the realm of possibility due to the combination of software control and constant connectivity that is the Internet of Things.

I'm talking about self-driving cars, which have been most notably advanced by Google's advanced research labs. A car is the biggest and costliest "thing" most people own outside of their homes, and yet it's barely connected at all -- streaming music doesn't really count. But we're not talking about one self-driving car or even a few of them at a time. The long-term goal of this technology is to completely replace human drivers, and it will happen in countries that realize the human and economic benefits.

Driving a car is one of the most dangerous things you probably do every day. Roughly 1.3 million people  die in road accidents every day, and anywhere from 20 million to 50 million more are injured. Google's self-driving cars have already proven to be safer than human drivers, with more than 700,000 accident-free miles on public roads compared to an average of roughly one accident for every 250,000 miles  driven on busy roads.

So far we've only covered the potential safety benefits of self-driving cars. The inefficiencies of human drivers cause Americans to waste roughly 5.5 billion hours  in traffic every year, at a cost of $121 billion in lost productivity. An optimized transit network of self-driving cars in constant communication with each other and with the road itself would go a long way toward eliminating these inefficiencies. A self-driving car would also be more efficient because it could simply come when called, servicing multiple people and spending much of its time active rather than sitting idle, parked for 90% of its existence.

Self-driving cars are a true killer app for the Internet of Things, and I can't wait to see them take over the roads.