Empirical research shows that if start-ups grow too fast the momentum can take the guts out of the culture, trip up the cause that drives it and stymie success.

FORBES: How Groupon Can Regain Ground

American investors are keen on high-tech start-ups because they have seen many grow into world-beaters.

ECONOMIST: London's high-tech start-ups

Congressional Republicans like Rep. Spencer Bachus were already seeking to allow more start-ups to grow into public companies.

WSJ: Kate Mitchell: How Silicon Valley Won in Washington

That increased use of technology in more mainstream fields is evident in the wide variety of tech start-ups looking to grow in New York.

BBC: Business

For example, online crowdfunding channels like Kickstarter.com and IndieGoGo.com can help start-ups land financing to grow.

WSJ: Are Small, Tech-Savvy Firms Top U.S. Job Creators?

But advance bookings may grow, thanks to a boom in start-ups competing to become the prime online aggregator of such transactions, such as GetYourGuide and Zozi.

BBC: Top sites for booking tours

Backing tested concepts mitigates the risk inherent in start-ups and means companies are likely to grow quickly, because the original firm has already worked out the kinks.

ECONOMIST: Making money by bringing old ideas to new markets

However, most of these start-ups will struggle to obtain the loans they need to grow, thanks to the shortage of credit amid the detox of the financial system.

ECONOMIST: The outlook for jobs in America: Help not wanted | The

Accordingly, UPS projected its holiday season package deliveries to grow 10% y-o-y to 527 million.

FORBES: Will UPS's Gains From E-Commerce Offset A Weak Economy?

In some ways, the Khan Academy and other start-ups are packing in some elements of these machine-based tutoring systems as they evolve and grow, such that this revolution is really already under way.

FORBES: How Machine-Based Tutoring Could Disrupt Human Tutors