This week Evensong is broadcast from the Priory Church, Edington, during the 2008 Festival of Music within the Liturgy. The link is here. Bookmark the BBC site, you will want to listen to Evensong each week. Trust me!
Also, Grace Cathedral, San Francisco, California, has an audio archive of the past week's services. Included is their weekly Thursday Evensong. The link for the audio page is here.