For finding generically related words, maybe the wordnik API? http://www.wordnik.com/words/mail#related http://www.wordnik.com/words/mail#related More abstrac

For finding generically related words, maybe the wordnik API? http://www.wordnik.com/words/mail#related http://www.wordnik.com/words/mail#related More abstract relationships (mail -> Cyrus, image -> Lenna) might be gleaned by crawling Wikipedia.