Electowidget is a plugin for older versions of MediaWiki designed to make it possible to conduct Internet polls and elections using many different voting systems, including the Schulze method, Instant runoff voting, Approval voting, and even plain old Plurality. It was actively developed (off and on) between 2005 and 2009, but has fallen out of compatibility with the latest versions of MediaWiki.
Electowidget wasn't designed for secure public elections. Rather, it was designed for the types of informal polls and elections that frequently happen happen online. It was also designed as a tool to help election theorists provide comparitive examples of how a given result will be tabulated comparing multiple different systems.
All data is stored on wiki pages, in JSON format. That means that there's an audit trail for every change that is made to the wiki.
Electowidget is licensed under a BSD-style license, with some GPL portions for MediaWiki integration. See LICENSE.txt for details.
Source code for electowidget:
When this plugin was actively developed, the official webpage was on Electowiki. The archival homepage has documentation about the configuration files and more details for anyone who is sufficiently determined to figure out how it works.
Electowidget is maintained by Rob Lanphier.