Blender incorporates Python as a scripting language. I've been fiddling around with it, and here are some of the things I've created. The scripts (in various states of functionality) are available on GitHub.
The automatic wall script (now ships with Blender)
Script for generating machine objects and assemblies (currently nonfunctional)
A complex tiling tool (currently nonfunctional)
realistic crystal geometry using convex planar volumes (fiddly)
I've been meaning to make a procedurally generated library for a while. This book is all hand-made, but should be pretty easy to codify, whenever I get around to it.
Free download for the book 3d model.
Complex Bookshelf script
You can download the Blend file from the BlenderArtists forum crazy bookshelf topic, as well as leave feedback and read a bit more about the script.
Or you can get it directly from my site.
I started this project to create decorative vines for a cabinet laser engraving project I was working on. Remarkably flexible! The Deco Vines code is on GitHub.
Once I had the design, I needed to be able to get it out of Blender and into the laser, so I also wrote a bit of Python code to export Blender meshes as G-Code.
Which I then engraved on some cabinets at the Meadow House. For more photos, see the Laser Engraving page.