Well, a number of years ago I attended a lecture at RTS (Charlotte) presented by Dr. Frank James on the topic of Calvin and Missions. This was wonderfully eye opening. Afterwards, I did a bit of research to follow up on this matter. I'm no scholar, and I don't have access to Calvin's correspondence, which is where James found the bulk of support for his lectures, but I did find some information on the missionary endeavor to Rio de Janeiro. Here are some links to a handful of articles on the subject.The lecture I heard is titled "The Calvin I Never Knew." You can download the audio files at itunes (http://itunes.rts.edu/). There are four parts.
Here is another article by Dr. Frank James - "Calvin the Evangelist."
Dr. Michael Haykin, a Reformed Baptist and church historian, has an (archived) article at Reformation21 on Calvin and missions.
Here are a handful of links lifted from Timmy Brister's blog:
John Calvin and Missions: A Historical Study by Scott J. Simmons
John Calvin's Missionary Influence in France by Michael Haykin (Reformation & Revival vol. 10 no. 4 [Fall 2001])
John Calvin and His Missionary Impulse by Erroll Hulse
John Calvin the Church Planter (doc) by Frank James