CollectBritain.co.uk: British Library sound archive examining the peculiarities and differences of regional English accents throughout the 20th century.
George Mason University: Accented speech of speakers from many different language backgrounds reading the same sample paragraph. Currently, there are 429 speech samples.
The New Okanagan College: English pronunciation and listening. A collection of videos and mp3 files about specific English sounds. For all foreign and domestic students who wish to improve their English.
The Speech Accent Archive: A large set containing hundreds of speech samples (English accents from native and non-native speakers and their phonetic transcriptions). Sound files and phonological information is included.