The initial gains of the 1990s dot-com boom proved sadly short-lived. (Pets.com sock puppet, we hardly knew ye!) But 15 years after it hit the mainstream, the Internet has nonetheless transformed the face of the business world, creating new opportunities and new market leaders. It may be too late to capture the heady initial growth of the best dot-com names, but what if we could find the next great industry before it reached the stratosphere?

On The Motley Fool's Twitter feed, Foolish follower @m_recruiters asked us:

Every decade has its boom industry ... Is energy the next the next ".com"?

We asked a panel of forward-thinking Fools to pick the next industry to hit the big time, and suggest one stock within that industry that might benefit investors the most. As always, please consider their selections as ideas for further research, not ironclad recommendations. Let's see where these Foolish folks think the future will take us.

The inescapable Internet
 Tim Beyers, Fool contributor and Rule Breakers analyst
For this tech writer, the coming decade's Next Big Thing is pervasive connectivity, and there are two main ways to play it.

First, you could bet on companies enabling connectivity through wireless infrastructure. Clearwire (Nasdaq: CLWR) and Sprint Nextel (NYSE: S) are building their national WiMAX network. Carriers AT&T (NYSE: T) and Verizon (NYSE: VZ) are working on alternative "fourth-generation" networks based on a technology called LTE. Unfortunately for all four, success depends upon massive capital investment, which means taking on debt.

Debt-dependent stocks scare me, which is why I favor a second strategy: betting on cash-rich companies whose products benefit from a boost in connectivity. Intel (Nasdaq: INTC) and Google top my list in this area. Google gets the nod only because, like Intel, it's already an investor in Clearwire and WiMAX. In addition, pervasive connectivity will expand the market for digital advertising, while allowing The Big G to sell more cloud-computing services.

"Old" is the new "new"
 Alex Dumortier, CFA, Fool contributor
I'm convinced that energy is a "next big thing," given that we will inevitably come to terms with the finite supply of existing energy sources. (Perhaps more quickly than anticipated!) Necessity is the mother of invention, and once we focus our ingenuity on this problem, I expect powerful and unexpected technologies to emerge.

That said, there's no set timetable associated with this "boom." And I'm convinced that just like the dot-com boom, the vast majority of investors won't make a penny trying to ride this megatrend.

For investors interested in earning solid returns from companies with limited business risk, I would suggest looking at "old energy" stocks instead. ABB (NYSE: ABB), for example, is one of the world's leading companies in providing electrification systems, from individual components all the way to entire solutions for managing transmission and distribution grids and power plants. Only a few large firms compete in these markets; furthermore, the opportunity in emerging economies is huge.

Cloudy with a chance of profits
 Anand Chokkavelu, CFA, Fool editor
Believe it or not, the company that may lead the next boom is one of the biggest winners of the last boom: Amazon.com (Nasdaq: AMZN). During the dot-com bubble, Amazon changed its public perception from "just a bookstore" to "the first place for everything retail."

So what's its next big transformational offering? Cloud computing. Under a cloud computing system, a company outsources much of their IT infrastructure (e.g. servers) and software needs to a third party. Amazon is a well-positioned early entrant in the space.

This business ain't so big yet, though. Non-retailing sales (including its cloud computing services) currently make up less than 3% of Amazon's total revenue. But Amazon's CEO Jeff Bezos is a visionary; aside from founding Amazon, he was an early investor in Google. So I don't discount Amazon's potential here.

Amazon's one of the few companies I'd pay up for, but at around 30 times next year's earnings estimates, it's still a bit pricey for my tastes. Still, if its stock price drops from here, remember that you're not just buying the dominant online retailer -- you're buying the dominant online retailer with a foot in the door in cloud computing.

You've got questions, we've got answers!
Thanks to @m_recruiters and all the other Fools who've sent us questions via our Twitter feed. If you've got questions about investing or personal finance, we'd love to help. Tweet them to us @TheMotleyFool, or leave a comment in the box below! And stay tuned for the second part of this article tomorrow, with even more great ideas for the next market-shaking industries.