Everyone who speaks a language, speaks it with an accent. George Mason University's Department of Linguistics has created The Speech Accent Archive, which uniformly exhibits a large set of speech accents from a variety of language backgrounds.
This website is of great use to ESOL teachers, speech pathologists and other school staff as it allows them to explore and compare the demographic and linguistic backgrounds of speakers in order to determine the variables that are key predictors of an accent. This site demonstrates that accents are systematic and not merely mistakes in speech.