But consider this little-known fact: Internet users spend a mere 5 percent of their time actually searching. The rest of the time, they're trolling the vast expanse of Internet space, leaving marketers ever more opportunity to fill it with display ads.

"Marketers now all have to understand the power of algorithms," she says. Today everything about a fully realized Web campaign - how the creative messages look, what color the ads are, what sites they're placed on and where on each site, what time of day they run and how frequently - is determined at least in part by software applications known as "creative optimizers."

And every big media company is paying attention. The fact that Google doesn't (yet) dominate the market for display ads is only accelerating the arms race for faster, smarter, more efficient ways of building and deploying display ads. Yahoo, the perennial No. 2 in paid search, already brings in an estimated $1.5 billion from selling ad space mainly on its own sites, and would love to see that number surge. Analysts estimate that Time Warner's AOL unit, long the ugly stepchild of its corporate parent (which is also Business 2.0's parent), will generate $1.6 billion from display ads this year, much of that from selling ads on third-party sites. From mighty Microsoft (Charts) to a host of tiny startups, everyone is racing to build a better display ad.