http://accent.gmu.edu/: Samples of speakers of many dialects and first languages, all reading the same English text, 69 words long.
http://polyglot.lss. wisc.edu/dare/dare.html DARE excerpts: Arthur the Young Rat and spontaneous speech
http:/ /www.pbs.org/speak/seatosea/americanvarieties/DARE/# -- small # of longer spontaneous speech samples from DARE
http://www.ic.arizona .edu/%7Elsp/index.html Some varieties have samples; not all
http://www.otago.ac.nz/anthropology/Linguistic/Sounds/Sounds4.html New Zealand, Australia, "England", "American"; all reading the same passage, 3-4 sentences long.
http://www.fonetiks.org/ "American", various UK, other languages
http://www.uga.edu/lsava/Topics/Language%20Variation/ Language%20Variation.html: videos of Ocracoke, Lumbee; discussion of Spanglish and verb tenses
Other links are possible from Karen Chung's homepage, under 'accents' http://ccms.ntu.edu.tw/~karchung/linguistics%20links.htm span>
Also, try the links from the American Dialect Society www.americandialect.org
Also, have a look at the MLA's wonderful, interactive color maps of languages in America. You can type in zip codes and get user-friendly but detailed language breakdowns based on census data of the 30 most commonly spoken languages in the US. www.mla.org