The ethics of Hermann Cohen were the topic of a conference held at the University of Toronto, in 2001. The proceedings of this conference are now available in form of a thematic issue of the Journal of Jewish Thought and Philosophy (volume 13, numbers 1-3, 2004), guest edited by Robert Gibbs.
See http://www.ingentaconnect.com/content/brill/gjtp/2004/00000013/f0030001.