Place Highlight

Pick any light source you want to align, activate the tool by clicking "Place Highlight" button. Hover mouse over any mesh in the viewport and press'n'drag LMB. Selected light source will be aligned in a way when specular highlight will appear right under mouse cursor position.

Place Object

Pick any object which can be Mesh, Empty, Curve or Light, and activate the tool. Object will be placed on the surface under mouse cursor. You can use Ctrl+Z to undo object spawn.

Replace Objects

Select objects you want to replace, then select a source ("Actrive" object) and press "Replace Objects". Selected objects will be replaced.
"Linked Duplicate" - create a Linked duplicates instead of regular copies.

"Remove Targets" - remove objects which was replaced.

"Ignore Scale" - ignore initial scale of replaced objects.

"Ignore Rotation" - ignore initial rotation of replaced objects.

"Ignore Modifiers" - remove all modifiers from source ("Actrive" object) object.

Spawn on Faces

Go to "Edit Mode", select faces on which you want to spawn an objects. Hold "Ctrl" and LeftClick on any mesh in the viewport, then press "Spawn on Faces" button. 
"Use Tangent" - align spawned objects to faces tangents.
"Linked Duplicate" - create a Linked duplicates instead of regular copies.
"Scale by Face Area" - try to match spawned objects to the size of the faces.

"Use Bounding Box Center" - use bounding box center of the faces instead of median point.

Vertex Bisect
Go to "Edit Mode", select faces which you want to bisect and press "Set Faces" button. If you not sure which faces are currently picked for bisecting, press "Retrieve Faces" which will clear all current selection and select all faces which is currently set for bisection.
Then switch to "Vertex" mode and select some vertices. Press "Bisect" button to see the result. Mesh will be bisected by multiple invisible planes based on selected vertices. 
Change "Plane" and "Space" setting in Undo-Redu panel as needed.
"Plane" - XY, YZ, XZ set virtual planes normal. View V (V - Vertical) / View H (H - Horizontal) - orient planes vertically or horizontally in screen-space.
"Space" - Local is using object local rotation. World - use world axis.

Fix Corner / Create Corner
Go to "Edit Mode", select edge which form a "corner":

Press "Fix Corner" and selected edge vertices will be aligned to make a perfectly straigth corner:



You can create new "corner" by using "Create Corner" function.
Select 2 non-connected edges:


And press "Create Corner":
The new 2 faces will be created and "bridge" 2 edges automatically.

Edge Length

Edge length operator are provide you ability to:
"Add or Subtract"  - where each edge length will became larger or smaller.
"Set" - where length for each edges will be replaced by new value.
"Scale" - where edges will be scaled.
"Offset" - where edges will be moved/"shifted". Notice what "offset" mode are mandatorily require edges to have a "Pins" on one side which is needed to determine direction for offsetting.
By default without "Pins" all operations (excluding "Offset") would change edges length from their center, i.e. the center between each edge vertices:
Here a "blue" object represent original mesh, and "white" was altered by using "Add/Sub" mode. No "Pins" was used.


To perform changing of length in certain direction we can select some vertices and press "Pin":


Now performing the same "Add/Sub" operation will keep "Pinned" vertices in place, but the "free" ends of the edges will be moved:


Interactive mode
Perform the same operations with a modal operator which also allow you to visually see "Pinned" vertices.

Delimit & Select
"Edge Loops / Edge Rings" - perform a regular loop selection, but propagation of selection is limited/"terminated" by picked "delimits", such as edges marked as: Sharp, Crease/Bevel Weight (any value bigger than 0), UV Seams. 
"Flood" - perform a selection similar to "Select Linked" but allow you to pick extra "delimits", such as Bevel Weigth or Creased edges.
"Connected" - perform a selection of any directly connected edges which have the same attributes, such as: Sharp, Seams, Bevel Weight, Crease, Border (border of the mesh). Any other edges on the mesh which have the same picked attribute but not directly connected to initial selected edge - will be ignored. 
"Rings to Loops" / "Loop to Polystrip" - extra helpers to perform selections. Rings to Loops - will turn edges in a way they will form a loops. Loops to Polystrip - will turn selected edge rings to polygons.