Last month Yahoo! announced BOSS, its Build Your Own Search Service, which "allows developers and companies to create and launch web-scale search products by utilizing the same infrastructure and technology that powers Yahoo! Search." The REST API allows developers to get results in XML or JSON format for web, news, and image search queries. Recently the official Yahoo! Search Blog showcased a handful of the best mashups that third-party developers created in BOSS's first month of operation.
Online stalking has gone programmatic. People search engine Whoozy has a person search API. With it, you can get results for a name from social networks and blogs, in addition to standard search engines.