During the 2012 and 2014 offerings of this course, I invited my students to write about the history of cryptography for Wonders & Marvels, a history blog edited by Vanderbilt professor Holly Tucker. The original posts, with comments, are available on Wonders & Marvels. The posts are also available here as a back-up.
During the 2010 and 2015 offerings of this course, I asked my students to collaboratively build a timeline of the history of cryptography. The timeline uses a Google spreadsheet and TimelineJS. (The 2010 version, with a different interface, is also available.)
Each offering of the course has used Simon Singh's The Code Book as a textbook. Reading questions for most of the chapters are available here.