(*) The Corpus of Contemporary American English (COCA) is the largest freely-available corpus of English, and the only large and balanced corpus of American English.
Based on 425 million words.
http://corpus.byu.edu/coca/

(*)The British National Corpus (BNC) is a 100 million word collection of samples of written and spoken language from a wide range of sources, designed to represent a wide cross-section of current British English, both spoken and written.
http://www.natcorp.ox.ac.uk/

(*) Frequency lists:
http://ucrel.lancs.ac.uk/bncfreq/flists.html

(*) Word frequency lists and dictionary from the Corpus of Contemporary American English
http://www.wordfrequency.info/

cdn.