WikiSeek a search engine that searches Wiki articles as well other web sites that link to WikiPedia. I am really uncertain of the practicality of this service. But it is a feature that I am sure could serve some educational purposes as well.
Their pages is definitely richly decorated with adwords. Regarding adwords, I am not sure about all of WikiSeek’s results quite yet, since I had more correct hits on some of my searches appearing in the ads, that in the real search results.