DuckDuckGo Zero-click Info includes topic summaries, categories, disambiguation, official sites, !bang redirects, definitions and more. You can use this API for many things, e.g. define people, places, things, words and concepts; provides direct links to other services (via !bang syntax); list related topics; and gives official sites when available.
Decorate texts automatically and and trustlinks to them. Moreover find some nice Domain information like Pagerank, IPv4, IPv6, Domainage, CountryCode (Hosting) and WOT.