is there any scripts that allow you to make a mesh bumpy (like the fractional subdivide option in blender – but that all ways goes to one side)
You can do it without a script using Noise in the edit buttons with a texture.
And yes, there are lots of scripts, too many to list. Search here in the Python forum for “Noise”, “Terrain” or “Displacement”.
Some I can remember offhand:
DisPaint or SCPaint