Normal Tools is a collection of MEL-scripts that speed up the process of manipulating polygon vertex normals. These tools are designed for low polygon work.
01 Installation
You should see Normal Tools menu appear in the main menu bar. This gives you access to all features included in the script.
02 Documentation

fig.01 - Normal Tools UI layout
Normal Tools UI is a floating window carrying every command you'd use in tweaking normals. By binding migNormalToolsUI(); command to a hotkey you can toggle this toolbox on and off.
Maya's default tool section doesn't include the Set Normal -command, because this is being replaced by Type-in Dialog. Also, the Soften Harden command is replaced by the Fillet and Maya's Average tools, which gives far more greater control over how to smooth polygon edges.

fig.02 - Type-in dialog layout

fig.03 - Planarize
Type-in dialog is a UI for setting vertex normals by value. It allows copying and pasting normals and a quick way to orient the normals along the major axis. By binding migNormalToolsTypeIn(); command to a hotkey you can toggle this toolbox on and off.

fig.04 - Before fillet
Faceted look

fig.05 - Fillet inside

fig.06 - Fillet outside
The Fillet command is a way to smooth polygon edges utilizing a different approach compared to Average and Soften Harden tools.
The command works on a polygonal face selection (yellow face in fig.04), but affects only the selection border vertices. The border vertices are smoothened through moving either the vertex-face normals that are included in the face selection or the vertex-face normals that are not included. This depends on the type of the command in question: Fillet inside [migNormalFillet(0)] or Fillet outside [migNormalFillet(1)].
Fig.05 and fig.06 show the resulting normals and a profile of the object demonstrating how the smoothened object will render to look like as though it was geometrically built like the curves indicate.


fig.08 - Bulged and pinched faces
Bulge is a command you can use to create the effect that faces were to bulge outwards or pinch inwards. This is achieved through spreading the normals outwards or pulling them towards the center of the face. See fig.08.

fig.07 - Bulge dialog layout

fig.10 - Randomized vertex-face normals on a sphere
Randomize works on vertex or vertex-face selection. When applied on a vertex-face selection the result is faceted as seen in fig.10.

fig.09 - Randomize dialog layout