GECO : Grasshopper to Ecotect

A free plugin for Rhino and Grasshopper allows the exchange of Grasshopper-powered Rhino models with Autodesk Ecotect, an energy and building performance analysis software, targeted at early design evaluation.
Read about it on:
http://www.rhinojungle.com/profiles/blogs/gh-plugin-geco-gh2eco-and-vice

When going over to the actual blog where the software is shared (http://utos.blogspot.com) you can read that the software is shared with a Creative Commons license (CC-NC-BY-SA). So free to use and share, but only non-commercial and shared under the same license.