ValueClick Stock Soars

And while the price tag takes a definite backseat at Microsoft -- which has boatloads of cash but has struggled to break into the booming online ad market -- who could have given the software giant such a run for its money?

Before Thursday, Time Warner's(TWX Quote) AOL division may have seemed like the knee-jerk candidate. But traditional online ad firm WPP's (WPPGY Quote) acquisition of 24/7 media for $649 million throws the door open to a host of new companies beyond the big name Internet suspects.

Old world ad companies like Omnicom(OMC Quote) and Interpublic(IPG Quote) may now be in the running to add an online ad property as well.

All of that bodes well for ValueClick, which, with a market cap of $3.3 billion, has the heft to give its suitor an overnight footprint in its fast-growing business. But if the market's reaction to the 24/7 Media Deal and Microsoft's willing to shell out a premium is an indication, that may not be enough.

More to the point, investors have a reason to take a close look at ValueClick even if a deal is not in the works. As the last major independent player in the space, ValueClick may serve as a haven to DoubleClick and aQuantive customers who do not want to take the risk of having their online stats shared with Google and Microsoft -- companies they see as competitors.