Project: Blender Extensions
Tracker: Py Scripts Upload
Category: 3D View
Script name: Centroid (Geometric Center)
Wiki page: http://wiki.blender.org/index.php/Extensions:2.5/Py/Scripts/3D_interaction/Centroid
Author(s): Martin Bürbaum
Calculate the centroid (geometric center) of a mesh object.
The original script (1.0.1) has only one new operator:
"Snap Cursor to Centroid"
... which does exactly what the name says.