(No real section, needs to be fitted in the right place in the manual-cw-)
The Subdivide Smooth function can be called with the WKEY in
EditMode. It has effect on all selected vertices and will
subdivide, like the normal subdivide but also rounding the
edges. Therefore you can adjust the percentage of the smoothing
effect with a NumberButton in a range from 10 to 100% percent. The
next picture shows the effect on a simple cube.