

Mathematical disasters - araneae
http://timesonline.typepad.com/schoolgate/2009/11/the-10-biggest-mathematical-disasters-in-the-world.html

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hegemonicon
The millenium bridge was not simply a case of a bridge designed in 2-d instead
of 3-d (it would have had to be designed in 3-d to account for wind loading).
It was a math error, but it was much more complicated - essentially, the
slight sideways motion people imparted to the bridge while walking caused the
bridge to sway slightly, which in turn caused the people to walk in step with
it, creating a positive feedback loop.

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InclinedPlane
The article describes the superconducting supercollider as a forerunner to the
LHC, however the SSC was designed to produce collisions with over 3x the
energy of the LHC.

Also, I'm surprised the Ariane 5's first launch didn't make this list:
<http://en.wikipedia.org/wiki/Ariane_5_Flight_501>

Inertial guidance code and systems were reused from the Ariane 4, but the
greater thrust of the Ariane 5 caused a 16-bit signed integer value to
overflow resulting in a cascade of problems culminating in the loss of
attitude control and destruction of the launch vehicle.

