Updated 20-Sep-2023
There are several white label options for search and if one considers advertising a viable business model to engage in, then consider Bing or Infospacehttp://www.infospace.com/partners/. Consider the case of Izito and related country code tlds, as well as MonsterSpace, both are pure play partner deals with nothing technical in their own right, with traffic and profitability. The best numbers come out of www.ecosia.org, which publishes their financial reports. I guess if the alternative is a search engine that doesn't provide some kind of additional value, that would be good. For sheer scale it is important to do a general purpose search engine. And then also having some level of curated content overlaid that would be black-hat proof, as well as some kind of vetting of ads?