Microvellum's Fluid Designer now has support for parametric objects. They demonstrate them in this video and I have to say it looks impressive!
Andrew Peel writes:
Demonstration of Parametric Modeling with Fluid Designer.
Fluid Designer is an application that is built as a plug-in to Blender (www.blender.org). The main purpose of the application is to provide users with an intuitive and streamlined way to design parametric libraries that can be used for 3D Design. More information can be found on our website or on our YouTube channel.
Some models used in the final render can be found in Blender Guru's Architecture model pack @ Blenderguru.com