Microsoft Chief Executive Steve Ballmer made a pitch to a collection of the world's top advertisers that his company is in the best position to bring together the different marketing opportunities offered by the Web, mobile phones, video gaming, and television.

"All of our marketing customers kind of wish there was one thing you could promote on called the Internet," Ballmer told about 200 agency and brand advertising executives today at Microsoft's Imagine2011 conference on the company's campus. The way it works now, advertisers have to gin up different approaches for different mediums, buying ad spots in a disjointed set of ways. "We have to make the Internet better in order to have it grow to be the standard platform for marketing," Ballmer said.

Microsoft, which generates $3 billion in ad revenue annually, is working on "the commercial glue" to buy advertising for campaigns easily across multiple devices, Ballmer said. To that end, Microsoft rolled out the latest version of Microsoft Advertising Exchange, that's now been integrated with the real-time bidding system of AppNexus.

Though Microsoft remains far behind Google in online advertising sales, the business generates $3 billion in annual revenue for the software giant. "It's the most rapidly growing part of our business. It's superimportant to us," Ballmer said.

That's why Microsoft holds the annual advertising gathering and trots out Ballmer to pitch the company's advertising business. It will show off not just its advertising tools, but technology such as Windows Phone 7, Xbox, and Bing, where advertisers can sell their message. And it's brought to Redmond big thinkers, such as Rhode Island School of Design President John Maeda and Academy Award-winning filmmakers Brian Grazer and Ron Howard, to lure ad executives to the meeting and get them to think broadly about new opportunities.