Refinery CMS is a Ruby on Rails content management system that started at Resolve Digital in 2004 (https://resolve.digital/). It was closed source for 5 years before becoming open source in 2009. It has quickly become the second most popular Ruby on Rails CMS and is growing rapidly. The project is contributed to nearly daily as it is core to Resolve Digital's business.
The project focuses on making the end user experience simple and understandable and offers developers brilliant tools to get a site developed quickly.