http://accent.gmu.edu/browse_atlas.php is a cool site that has recordings of many people reading the same passage of English text, to provide samples for determining accents. Information is recorded about the person’s native language and how they learned English. You can find the samples by browsing on a world map, searching by native language, or doing more sophisticated searches (by age, gender, other languages, how English was learned, and so forth).
It is a great resource for theater students who need to hear a regional accent, as well as for linguistics researchers. Some of the samples have phonetic transcriptions and some of those have been annotated, to indicate the ways in which the accent differs from “standard” English.