As we process applications for the 2011 Inc. 500 | 5000, we thought it would be worthwhile to shine a spotlight on some of the companies that are vying to appear on our ranking of the fastest-growing private companies in the United States. One that caught our eye was New York City-based HopStop.

When Nigerian-born entrepreneur Chinedu Echeruo first moved to New York City in 1995, the Harvard Business School grad was quickly introduced to a problem already familiar to the millions of other city dwellers. Car-less, Echeruo was forced to rely on alternative forms of transportation. At the time however, there was no MapQuest-type service that gave directions linking public transportation, such as buses, trains, and subways.

An opportunistic entrepreneur, Echeruo realized the market for such a service and launched HopStop in 2005, a door-to-door directions platform that stitches together data from various transit agency sites, providing one cohesive navigational experience.

"The majority of our users are usually active and on-the-go, going to events, restaurants, social events, ball games, clubs, bars, restaurants, points of interest, and tourist attractions," says Joe Meyer, CEO of HopStop. "They need to know how to get there—or get from there."

HopStop has been a hit among the metropolitan markets—especially in New York, where it all began. By providing thorough, customized directions to get from Point A to Point B, HopStop's popularity has soared in recent years, resulting in doubled revenue in each of the last three years, as well as profitability and positive cash flow. Despite being in existence all of six years, the company is a clear leader in the transit routing space.

"Under the hood, we're a data company," Meyer says. "We ingest data from over 35 different transit agencies throughout the New York tri-state area alone; not just the MTA. If you're going from Manhattan to Hartford, or from Montauk to Greenwich, there's probably 20 different ways you could take that trip using transit and pedestrian means, but the only way to present those different options is if you have access to all of the agencies."

Whether you're walking or taking the train, bus, regional rail, ferry, limo sedan, or taxi, HopStop provides routes based on each individual's preferences. Each chunk of directions is broken down contextually, providing landmarks and the expected duration time for each leg of the trip. However, should a user wish to diverge from the recommended route, users can easily modify any step of the journey.

HopStop accomplishes this multi-modal utility by aggregating massive amounts of data from several hundred transit agencies, including street-level mapping data from location-based service provider NAVTEQ. After compiling the data, HopStop converts address inputs to XY plots on a map. Depending on the user's preferred mode(s) of transportation, HopStop routes the user from XY to XY, plotting points on a map to form a route.

"We do a ton of internal testing before we release anything," Meyer says. "But the users banging away at it—in real-time, en masse—is the best way to test anything."

Users drive the HopStop experience by both using it and suggesting ways to improve it. Any messages, issues, or suggestions sent will usually receive a response within 24 hours.

"Any time we release a new feature, a new function, an enhancement, a new market, a new mode of transportation, or put a new transit agency into the system, the ultimate test is releasing it to millions of users," Meyer says. "The users are very vocal, and without them, we'd be somewhat flying blind, to tell you the truth."

Most user feedback leads to constant tweaks and dial turns to the platform, but other feedback results in completely new product innovations. For example, HopStop's latest feature, routes and directions for bike riders, was originally a customer request.

"If enough users are requesting it, that means thousands upon thousands of other users who aren't e-mailing us or telling us on Twitter probably want it too," Meyer says. "We have a fairly large presence on Facebook and Twitter and Yelp, and other platforms that give us real-time feedback from users. We read all of those points of feedback and we take action on most of them. We really are feedback-centric."

Despite its micro-staff of 15 employees, HopStop serves over 50 different market regions around the world. In the coming weeks and months, HopStop will redesign its site and open in more world markets. With the rising popularity of its mobile apps and its several other plans for expansion, HopStop is poised to dominate the transit routing market, if it hasn't done so already.

"We have more modes of transportation than Google Maps, which we think is key," Meyer says. "Our viewpoint is that depending on the trip and the route, sometimes one mode of transportation is really preferred over another. You really have to offer the user as many options as possible."