Over the past five years, it has done a few acquisitions of its own. In 2008, iCrossing expanded its European presence after purchasing German search and affiliate shop 3GNet. Before that, it acquired Utah’s Sharp Analytics and London’s Spannerworks in February 2007. Before that, iCrossing bought paid search marketer Newgate Internet and web developer Proxicom.

While the Hearst offer for iCrossing would seem to come out of left field, publishers like Meredith (NYSE: MDP), are increasingly looking to diversify their services. So even though the publisher appears out of the running for now, it’s safe to assume that the traditional ad companies looking iCrossing over could have some competition from other quarters of the media industry.

Still, for the moment, there is a reason to place a bigger bet on Japan’s Dentsu as the most likely candidate to win iCrossing. Even though Dentu’s $700 offer to buy Razorfish from Microsoft (NSDQ: MSFT) was bested by Publicis Groupe’s $530 million bid, the Japanese agency has expressed a strong desire to acquire a digital shop.

Meanwhile, WPP Group and Aegis have tended to concentrate their acquisition efforts in emerging markets, where online ad growth is still growing faster than in the U.S. and Europe. Still, online advertising expected to be up around 5.5 percent in 2010, according to eMarketer. Search’s growth will remain particularly strong, making iCrossing an even more appealing catch.