Moore's Law states that the number of transistors that manufacturers can put on a single semiconductor chip doubles about every two years. Although it's really just an observation or a prediction, this "law" has held true for almost 40 years. It's meant that computer makers can either double the power of their products every couple of years -- without raising prices -- or squeeze the same amount of computing power into ever-smaller and cheaper packages.

While 2005 was no exception to this trend, what made it unusual was that researchers, software engineers, and entire communities found innovative ways to take advantage of computing's growing power and falling costs. A few examples: research capitalized on the industry's better understanding of silicon and how to manipulate its properties; web programming projects made use of computers' increasing processing speed and networking capabilities; and people worked together to adopt and adapt maturing computing technologies to enhance social life and community.

Here are five stories we think exemplify these exciting and far-reaching themes.

Municipal Wi-Fi

About a year and a half ago, only a handful of municipalities were thinking about providing citywide Wi-Fi access. Now there are more than 300 U.S. cities considering municipal Wi-Fi, which would provide inexpensive wireless Internet access anywhere, for anyone: in a park, library, home, or car.

This year's most important development in Wi-Fi may turn out be the discovery in October that Google is bidding to fund a network in San Francisco, providing free wireless Internet access to all of its 750,000 residents. Google plans to pay for the project by selling ads that would be served to Wi-Fi users.

Indeed, many big Internet companies see business opportunities in municipal Wi-Fi. EarthLink was chosen to build the wireless infrastructure for Philadelphia -- a project that will be especially closely watched, since Philadelphia saw the most publicized clash over who has the right to build municipal wireless networks. Verizon, which runs Philadelphia's phone system, lobbied hard to keep the city government from building -- or even contracting out -- its wireless network, arguing that it would disrupt free-market competition. And the state legislature passed a law requiring Pennsylvania municipalities that want to build their own Wi-Fi networks to submit a plan by January 1, 2006, or be forced to get permission from the local phone provider.

Citywide wireless broadband access doesn't benefit just computer users, but also cell-phones users, a growing number of whom can receive wireless Internet data and can communicate on multiple frequencies, including Wi-Fi, says Dirk Trossen, who studies wireless networking at Nokia. Wi-Fi for phones would be appealing “not only for voice calls but also for citywide services, such as shopping guides," he says. "This would also enable cities to approach communities or shop owners to help deploy the city Wi-Fi -- or at least better argue for the benefits of such engagement.”