Open Source / Non-Proprietary
Acceleo is a code generator transforming models into code (MDA approach).
Acceleo is easy to use. It provides "off the shelf" generators (JEE, .Net, Php...) and template editors for Eclipse.
The module repository provides a set of "ready-to-use" generators targeting many languages and technologies:
UML to JEE Struts/Hibernate
UML to Java
UML to CSharp