Travel community site TripAdvisor has expanded its online territory over the past several months. The Expedia subsidiary announced that it has bought four travel media businesses, adding five travel community web domains. The company claims that the acquisitions have grown its audience to more than 24 million monthly visitors, citing numbers culled from comScore Media Metrix. The new properties are Boston-based Smarter Travel Media (purchased in February), operator of smartertravel.com and bookingbuddy.com; Seattle-based SeatGuru.com (buyout occurred in March); Ottawa, Canada-based TravelPod.com (which was acquired back in December); and U.K.-based Travel-Library.com, which TripAdvisor bought last September. Financial terms were not disclosed. Release