Free online courses - by category

http://www.class-central.com/ provides a complete list of free online courses offered by Stanford's Coursera, MIT and Harvard led edX (MITx + Harvardx + BerkeleyX), and Udacity

  Course counts by category:
  
  Category                                                NN %%
  Computer Science                                        81 38%  
  Healthcare, Medicine, and Biology                       29 14%  
  Physical & Earth Sciences                               16  7%  
  Humanities and Social Sciences                          16  7%  
  Economics & Finance                                     13  6%  
  Mathematics and Statistics                              10  5%  
  Statistics, Data Analysis, and Scientific Computing      9  4%  
  Entrepreneurship                                         9  4%  
  Society, Networks and Information                        8  4%  
  Electrical and Materials Engineering                     7  3%  
  Business & Management                                    5  2%  
  Education                                                4  2%  
  Complex Systems                                          3  1%  
  Chemistry                                                1  0%  
  Civil Engineering                                        1  0%  
  Physics                                                  1  0%  
  Design                                                   1  0%