The latest research from Nielsen//NetRatings shows that the time Internet users spend online at home in the U.S. has stayed flat, at just under 14 hours per month. By contrast, emerging Internet markets, including Australia, France, Hong Kong, Italy and Japan, have shown double-digit increases in time spent online at-home.

The survey found that the nearly 14 hours Americans spend online at home each month is close to the worldwide average. Of the 12 countries surveyed, those living in Hong Kong surf the longest, averaging nearly 22 hours per month. On the lower end, Italians on average log eight hours online.

The flat usage in the U.S. and other mature Internet markets, including Brazil, Germany, Spain, Switzerland, Sweden and United Kingdom, poses threats to Internet companies, who will have to innovate in order to drive more growth so that they can expand their revenues.

"As the Internet has officially become an important part of our lives, the U.S. is primed for the next 'big thing' to spike Internet usage," Kaizad Gotla, senior Internet analyst, Nielsen//NetRatings, said in a statement. "There are many opportunities ahead for companies online, but if they just continue to do what they're doing today, they're only going to move sideways.

"The easiest opportunities are in countries where Internet usage patterns and user/site relationships are less established. Acquiring users in markets that are currently in their growth stages will lead to a loyal user base that will pay dividends for Internet companies in the future," concluded Gotla.