Rimm-Kaufman defined "crumbs" as smaller, highly specific terms that can usually be purchased cheaply as part of a pay-per-click search marketing program. For a tabletop marketer, for instance, buying terms such as "tableware" and "flatware" may be obvious, but also more expensive. And the traffic generated by such general terms may have lower conversion rates. But crumb terms such as "Lenox china platter" tend to be cheaper and have higher conversion rates. They do have lower traffic, Rimm-Kaufman added, but in aggregate they can be more profitable than the more general phrases.

"Smart smaller companies can beat larger companies by being clever," Rimm-Kaufman said. First, though, you need to determine if people are searching online for what you sell. Some products, such as stamps, simply aren't frequently searched for via engines, he said.

Numerous online tools can provide rough estimates regarding how many times phrases are entered into search engines. From there, it's a matter of extrapolating the number of potential searches with estimated click-through rates and conversion rates to determine whether paying for a particular term is worthwhile.

International Auto Parts pays for more than 800 terms, Lee said. In keeping with the crumb philosophy, his company has found that specific terms, such as "Cherokee Jeep floor mat," outperform general terms, such as "floor mat."

"Ads that are too broad can really hurt you on a pay-per-click model," Lee said, since the conversion rate will be too low.

Lee said that 10% of the terms his company buys account for 80% of all its search-derived Web traffic. About 20% of International Auto Parts' new customers are coming to the company via pay-per-click search results.