The narrow perspective is one reason age-based portfolios are popular for college saving.

FORBES: Investment Guide

Both of these are based on short-haul, narrow-bodied types -- the Boeing 737 series and Airbus A320 series -- both of which seat fewer than 200 people in commercial passenger configuration.

CNN: Luxury living at 35,000 ft

To narrow the racial gap in swimming, the L.A.-based Amateur Athletic Foundation gives grants to swim facilities in Southern California.

NPR: L.A. Effort Narrows Swimming's Racial Gap

Should it become a broad-based national opposition, or a regional movement representing the narrow interests of its Western Cape supporters?

ECONOMIST: South Africa��s leaderless Nats

On a mobile device buzz.com could further narrow the field based on a person's location, using opt-in global positioning system data.

FORBES: Magazine Article

If your New York-based company needs a copywriter, a UX designer, or an AJAX developer with a very narrow, very specific skill set, that person can work just as well from Birmingham or Kansas City or Seattle.

FORBES: Why Investing In A More Mobile Workforce Makes Sense