There is this community called iteraplan out there which focuses on open source tool for enterprise architecture management (EAM). More details below….

iteraplan: Enterprise Architecture Management (EAM) Made Easy

Welcome to the community of iteraplan, the first open source tool for enterprise architecture management (EAM). iteraplan is based on the IT landscape modeling method developed by the consulting company iteratec.

iteratec will continue to improve iteraplan and will publish new versions of iteraplan as open source software on this community platform.

Transparency and control

Enterprise architecture management (EAM) helps you make your IT landscape transparent by offering methods and tools to analyze, redesign, plan and control your enterprise architecture. iteraplan implements a concrete EAM methodology we have developed based on our experience from many projects.

Business processes, information systems, interfaces and their technical realization form, besides other elements, the center of the underlying model. Thanks to its predefined structures, iteraplan can be used immediately and helps to quickly master the complex topic of EAM.

iteraplan offers the following advantages:

• iteraplan is released under an open source license. Hence no license fees have to be paid.
• Customization is fast and easy.
• Different user roles can have their preconfigured views on the IT landscape.
• Editing, analysis and redesign of IT landscapes are offered efficiently in different views.
• iteraplan is easy and intuitive to use and provides a fast introduction into enterprise architecture management.

External source: http://www.iteraplan.org/en