As part of my One hundred sketches project I have been playing around with Sverchok. A node-based parametric design tool for the Blender environment. While its a bit difficult to get use to, it does have some powerful features and has a lot of potentional.
Sverchok allow you to manipulate vertices, edges and polygons using vector/matrix math to create meshes. Because it relies on the Blender Python API you can actually integrate python code and use external data sources, via csv, JSON or even live network connection.
It definitely feels like something still under development but even with its current feature set it is a great way to integrate parametric approach into Blender.
Here are the blend files I used to for the images on this page.