Once considered an unsexy startup sector, adtech has been seeing increasing attention from VCs as of late. The latest recipient of an eight figure check is mobile advertising platform Medialets which today announced $10 million in Series C financing led by Greenspring Associates.

Medialets describes its offering as “spanning the full advertising campaign life cycle,” which in English means marketers can plan plan, book, and buy advertising through a single interface. Apparently advertisers and agencies are flocking to the product, with the company’s revenue over the first nine months of 2012 more than tripling from the same period a year prior.

The four-year-old adtech company powers the mobile and tablet campaigns of 300 of the world’s biggest publishers, including BBC, BSkyB, CNN, ESPN, The New York Times, The Wall Street Journal, The Weather Channel, and Yahoo, as well as “every major agency and holding group,” to use the company’s hyperbolic language.

Medialets previously raised $18.4 million from Foundry Group, 500 Startups, DFJ Gotham Ventures, and Bobby Yazdani, with the latest $8 million Series B round coming in August 2010. The New York City-based company, with offices in Los Angeles and Chicago recently opened an European headquarters London and will use the additional funding to accelerate its growth both domestically and internationally.

Where the majority of rapidly growing startups focus on user acquisition at the expense of monetization, the adtech industry is known for growing revenue quickly. In an environment where nine-figure exits by IPO or acquisition are incredibly scarce, it’s not surprising to see adtech cash cows attract the attention of savvy investors.