Or you'd have to go overbroad.
Cuil is dead, they've tried to re-invent themselves in april as an encyclopedia, I think they must have missed the memo about WikiPedia's continued success.
Their search results suck too...
Duckduckgo.com is larger than cuil!
If the price is right, almost any search can be monetized.
This is how 2nd tier engines like 7search make money, except they have too much low-quality international and bot traffic to give steady conversions.
ddg could easily monetize and attract lots of advertisers if they published their exact search data, keywords and counts.
Wordtracker is making a mint, millions and millions of dollars simply publishing dogpile.com search data, which has a tiny (1%) share of the search market.
SEMRush is scraping Google for search data and has over 70,000 customers.
Nobody else currently does this. Privacy concerns aside, if there were a search engine that had a good keyword tool designed for advertisers, it would attract ad money in droves.