The new Google Patent Search API is now available and lets you search over 7 million patents via code. It is part of the AJAX Search API suite of content-specific Google search utilities such as book search, government search, code search and others.
Factery is a search API with a twist. Instead of links, it returns facts. Actually, it returns links, too. But the real interesting stuff is that it extracts the sentence or two that best answers a user's search.