Someone sent me this video today, the English accents (e.g. ones from the UK) were perfect, as is the Nigerian accent! I wouldn't listen to it around your children though, as it is spoken by someone from London there is a lot of casual swearing. The American ones and the Aus accent are pretty rubbish though.
<YOUTUBE id="dABo_DCIdpM" url="http://www.youtube.com/watch?v=dABo_DCIdpM&feature=player_embedded">http://www.youtube.com/watch?v=dABo_DCIdpM&feature=player_embedded</YOUTUBE>
<YOUTUBE id="dABo_DCIdpM" url="http://www.youtube.com/watch?v=dABo_DCIdpM&feature=player_embedded">http://www.youtube.com/watch?v=dABo_DCIdpM&feature=player_embedded</YOUTUBE>