Smart entrepreneurs often see a tech tidal wave coming long before it hits the shoreline. Check out five emerging technologies below--and the companies that are using them to create new, burgeoning markets.

1. Google Fiber
Kansas City, Kansas, had the good fortune to be the first city to benefit from Google's super-fast 1Gbps Internet service. As the city gets fully wired--and the fiber network starts to spread elsewhere--tech start-ups are itching to see what they can do with it. One such company is 3D printing start-up Handprint, which won investor Brad Feld's contest to live in a fiber-connected house for a year to develop its technology. Of course, Fiber is still too new and its reach is too narrow to know for sure what may come from it. But I'll hazard a few guesses: Expect the fast connection to lead to new gaming companies, innovative cloud storage services, and maybe a new video social network.

2. Crypto-currency
You may already know about Bitcoins, encrypted pieces of data that work like currency. That's just the beginning--the market for "crypto-currency" is exploding. Companies like Tinker, which makes it easy to buy a Bitcoin, and, which provides a platform for exchanging Bitcoins, are just two examples. Expect many more to follow.

3. Alternative interfaces
The keyboard and mouse approach is getting old, isn't it? Even touch tablets are a little ineffective, especially for doing real work. Companies like Thalmic Labs, which makes a user interface that responds to muscle activity, and Leap Motion, which uses fine gestures (even with individual fingers) are responding in kind. The idea is to explore whole new computing interfaces that interact with people and their digital devices in the real world.

4. Lifelogging
Google Glass, the glasses that let you find a place to eat, get directions, and view incoming messages all with voice control, is an early example of how people are using devices to log much of their days. Now, more companies are getting in on the trend. Gadgets like the Memoto, which snaps photos throughout your day, and the FitBit Flex, which records all of your movements, are leading to a more quantified society--and new business opportunities.

5. Electric vehicles
Say what you will about the electric car market, there are now plenty of plug-in and all-electric models to make this market worth considering. (Consider the Ford Focus Electric, the Nissan Leaf, and the Chevy Volt to name a few.) And EVs have spawned a new ecosystem of companies to tackle the new challenges they bring. ChargePoint, PlugShare, Witricity, and Oceanus are a few to keep an eye on. As EV sales increase, expect to see more and more tech companies with an auto focus.