Classical Music Pages provides a brief narrative introduction to the Chorale here.
Texts of the Complete Vocal Works
This Bach site by Z. Philip Ambrose offers English translations to the vocal works of J. S. Bach along with introductory information on the sources and performance history of each work.
A Listener's Guide to the Cantatas of J. S. Bach
Simon Crouch's article includes indexes, descriptions, links, and a bibliography regarding Bach's cantatas.