I need to add full web search to my site. I need something like Google Custom Search but with no ads and it has to be free. Any recommendation of a web service or open source project that can index my site and allow me to search it will be helpful.
My site is made in ruby on rails, if that helps.
I’ll make this question community-wiki so you can edit my bad English. I think many people can benefit from this question.
Depends what you mean by full web search really. If you want to search the whole web then the answers above wont help you much as they are really for indexing and searching the content of your site. I would suggest using the Google ajax search (just a ‘powered by google’ needed, no ads) or Boss from yahoo (might require ads not sure).
http://code.google.com/apis/ajaxsearch/
http://developer.yahoo.com/search/boss/