The September acquisition of Blue Lithium by Yahoo for $300 million, like AOL's takeout of Tacoda in July for a reported $275 million, put a spotlight on ad networks that let online ad buyers use something other than keywords to find potential buyers.

These behavioral-targeting networks are seen by many as the next step in the evolution of online advertising, and the price Yahoo paid showed how valuable they could be.

Tumri's approach is slightly different, says CEO Hari Menon, because it allows online retailers to generate ad units directly from catalogs and other product listings.

The company's technology can "go deeper," drilling down to the specific product level, Menon says. 

For example, a women's apparel seller can offer ad buyers placement next to a specific type of spring jacket in their online catalog, rather than forcing them to buy the keyword "women's  spring jackets" from one of the big ad networks.

Tumri's algorithm can also incorporate user data, so that the ad in the example above wouldn't be served to users known to be men. 

The ad units can be derived from a range of listing -- from real estate properties to automotive classifieds. One of Tumri's clients is PC maker Lenovo, which generates ads based on its product listings.

The company's ad network of 200 million page views, "is not very large, but it's growing at a fast clip," Menon says.