Here's another similar idea, someone please do this: a search engine that excludes all "commercial" sites. "Commercial" means the site contains ads or accepts payments.
Even of you refined your criteria, what do you have against sites that try to recoup costs of hosting or content? Or, are you referring to completely different sites, lumping them all under "commercial sites" label?
More generally, I don't have anything against any sites, I'm trying to come up with a way of viewing the internet that would have a high signal to noise ratio. It seems plausible to me that excluding all sites with ads would improve the signal to noise ratio over what we have today. If you think the signal to noise ratio would be improved further by carefully including some sites with ads (SO is a good example), can you take a stab at defining the criteria?
Maybe include only sites whose ads are deemed acceptable by adblock? But then we might include many content farms...
Your idea started out good. Sometimes I want to research a product before I go looking for a merchant. Blocking all sites that contain ads? Just use adblock if you're that fanatical.
I think it's a good idea. It'd certainly help with the problem of blogspam etc.
As the owner of a search engine I can tell you search ain't cheap.
Bikeshedding I say!
If we're just making something interesting and different, not shooting to replace all search, imperfect definitions are a wonderful place to start.