From Linux.com, a short entry on an open source workflow manager:

ProcessMaker is an open source workflow manager that works either on the client side or as a hosted application. Founder Brian Reale began developing ProcessMaker in 2002 after working with the South American Telecommunications Regulatory Institution to create a “paperless office.” Once that system was deployed, Reale thought he could create an affordable standalone product that would make it easy for users to eliminate paperwork and create a more efficient workplace. Reale built the new product using open source software, and has licensed it under the GPLv3.

Additional info from the ProcessMaker website:

ProcessMaker is a commercial open source workflow and business process management software suite that allows private and public organizations to automate document-intensive, approval-based processes across systems including finance, HR, and operations. Entirely web-based, it allows users across multiple sites to create and share workflows, customize forms, manage processes, and enhance reporting.
ProcessMaker includes tools to design forms, create documents, assign roles and users, create routing rules, interconnect with third-party systems including business intelligence (BI), document management (DMS), content management (CMS), and enterprise resource planning (ERP) systems through a service oriented architecture (SOA), and to map business processes quickly and easily.