“There has long been a cat-and-mouse game between Web advertisers, which pay to place their messages on sites where people view content, and ad-blocking services, which let people hide those messages from their browsers. Steve Lambert, a conceptual artist, plans to add his own twist to one type of software that blots out commercial messages. His add-on will replace the display ads — which are usually papered over with blank windows — with curator-picked artwork from contemporary artists.”