A computer algebra system written in pure Python http://sympy.org/ . To get started to with contributing https://github.com/sympy/sympy/wiki/Introduction-to-contributing

Mailing List Drupal module | https://drupal.org/project/mailing_list | Collaborated repo for coderspuebla.com

Program to securely send and receive HTML e-mails (and of course normal text e-mails too)