The spectacularly complex mathematically generated columns of Michael Hansmeyer were featured recently in an Inhabitat article "Incredibly Intricate Cardboard Columns Are the World’s Most Complex Architecture". The columns are generted through geometric algorithms then cut from thousands of layers of cardboard - when assembled the incredible patterns weave into existance.
Apart from being able to generate this level of complexity, I like the fabrication and being able to actually bring something like this into reality and out of the computer.
[Michael Hansmeyer column images via his website]
Here are some more images from his work with algorithms and geometry in his platonic solids series:
[Michael Hansmeyer complex platonic solid images via his website]
Here is an older video showing how some of this complexity arises as the maths has fun with a sphere: