As an operating company of Expedia, Inc., the TripAdvisor Media Network now encompasses some 32 million monthly visitors, according to comScore Media Metrix.

Steve Kaufer, founder and CEO of TripAdvisor, is excited about the addition of VirtualTourist and its community of over a million users. "VirtualTourist pioneered the concept of an online travel community," Kaufer said.

Niche travel sites and blogs appear to be selling like hotcakes these days. For example, CondeNet, owner of Concierge.com and CNtraveler.com, recently acquired HotelChatter.com and Jaunted.com.

The TripAdvisor network's other sites include TripAdvisor.com, AirFareWatchdog.com, BookingBuddy.com, CruiseCritic.com, HolidayWatchdog.com, IndependentTraveler.com, OneTime.com, SeatGuru.com, SmarterTravel.com, Travel-Library.com, TravelPod.com and VirtualTourist.com.

VirtualTourist and OneTime, both based in Manhattan Beach, Calif., each claim to operate profitably from the generation of online ad revenue. There are no plans for integration of the businesses or the Web domains.

VirtualTourist General Manager Giampiero Ambrosi and OneTime General Manager Dena Yahya will continue to run the businesses, respectively, reporting to Kaufer. The employees of VirtualTourist and OneTime will remain based in Manhattan Beach, Calif.

"Combining efforts, we hope to accelerate growth," said J.R. Johnson, founder and chairman of VirtualTourist and OneTime, referring to the acquisitions.

In 2004, Barry Diller's InterActiveCorp agreed to buy TripAdvisor to bolster its existing travel properties, including Hotels.com, Expedia and Hotwire.