Microsoft has bought Navic Networks, a move that puts it in the business of placing TV commercials in near real-time, one of the things that Steve Ballmer may have had in mind when he said there were a lot of things you could do with $50 billion besides buying Yahoo.

Navic’s applications make ads interactive. It also collects data to tailor ad campaigns and measures ads’ effectiveness. It’s got a platform called Admira for targeting ads to audiences by demographics and what they’re watching via set-top boxes and partnerships with cable and satellite TV companies that reportedly put its widgetry on 35 million set-top boxes in North America.

It can effectively aggregate an audience.

Terms of the acquisition were not disclosed but Seeking Alpha puts it at between $200 million and $300 million.

Navic will be a wholly owned subsidiary and part of Microsoft’s “cross-platform” Advertiser and Publisher Group under ex-aQuantive CEO Brian McAndrews. The unit also includes Atlas and its video-on-demand advertising solutions.

TV commercials still claim the biggest slice of advertiser and ad agencies’ media budgets, some $70 billion a year, as Microsoft couldn’t help but observe. Online advertising is only worth about $20 billion.

Apparently the idea will be to drive digital advertising across online and offline environments.

Navic employs 82 people and raised $43 million in venture funding.

Google’s recently come up with its auction-based Google TV Ads operation and a deal with Dish Network.