Ever feel the need to book your ground transportation from the airport while you’re still sitting on the runway? Or pay a taxi fare with a click of one button? Maybe not. But that’s the concept behind RideCharge, maker of TaxiMagic — an app that lets business travelers book and pay for ground transportation from their mobile phones (iPhones, Blackberrys and phones running Windows Mobile, for now). The Alexandria, Va.-based company just brought in $4.6 million in second-round funding to bolster its marketing campaign.

Most of the new funds came from Concur Technologies, an automated travel company that can make restaurant reservations via OpenTable, save airport parking sorts through Park N Fly, and connect travelers with rental car, hotel and rail reservations through a variety of vendors. Concur’s mobile technology also provides users with e-receipts for any purchases made on their phones with its services. This goes for TaxiMagic too. When the meter registers a final fare, users hit one button to automatically pay the driver, and a receipt is delivered to their inbox as a PDF file.

RideCharge says this service is currently available in 30 cities in the U.S., where it works with many large taxi, sedan and shuttle companies. In addition to booking and payment capabilities, TaxiMagic lets users track the GPS location of cars they have ordered. The app has been downloaded about 10,000 times per week since its launch last June, the company says.

The recent investment round was led by Concur, and included an undisclosed venture firm and unnamed angel backer. RideCharge has raised $8.5 million to date, which its executives say may be enough to last it to profitability by the end of 2009. With only 15 employees and no formidable competitors, this looks like a reasonable enough goal.