British National Corpus. A large (100 million words) corpus of modern English (1990's). Includes an online component. Also available online with an excellent interface here. See also BNC Indexer
International Corpus of English A major project directed by Gerald Nelson. Some corpora can be downloaded (under licence) -- Hong Kong, East Africa, India, Phillipines, Singapore. Others are available on CDROM -- Great Britain and New Zealand.
Oxford Text Archive WEB site Good starting point for British novels: Dickens, Trollope, etc.
Susanne Corpus by Geoffrey Sampson
OED Online Subscription ($30 a month is one option)Free eBooks - Project Gutenberg 17000 books
Project Gutenberg of Australia
Corpus of Spoken, Professional American-English The corpus is available commercially from Athelstan. There is a 50,000 word sample available online. This two-million word corpus can be used for lexical and grammatical analyses, but not for close discourse analysis as there is no backchannel, overlap, pause length etc,
Renascence Editions Worked printed in English between 1477 and 1799Wellington Corpus of Written/Spoken New Zealand English.
Penn-Helsinki Corpus of Middle English
The Lampeter Corpus of Early Modern English Tracts
ICAME, Bergen. An important site. Contains info on the ICAME CDROM and archives of the corpora list.
The Bergen Corpus of London Teenage Language
Corpus of Written British Creole Contact Mark Sebba to obtain the corpus
The TRAINS Spoken Dialogue Corpus
CCAT Archive Gopher site at U. Penn.
Voice of America News (Gopher)
CBC Canadian broadcasting archives. Includes sound files.