just showing here for some tools i did during my work.
i'll post the script later.
1:Grass Layer tools: create a layer mesh based on selected edge and apply uv channels automaticly.
2:Randomize Tool: Align to the selected surface and randomize by position, rotation and scale.
3:Ground Clutter Tool: By customized particle flow in a simplified UI, it's easier for artist to create specified task like this.