Headers and Footers sets options for printing a notebook.

Insert > Horizontal Lines (Mathematica Menu Item)

Horizontal Lines opens a submenu to insert a line of the specified thickness above or below the selected cell.

Insert > Hyperlink... (Mathematica Menu Item)

Hyperlink creates a hyperlink to a specified cell, notebook, or URL.

Initialization Cell makes a cell auto-evaluate whenever the notebook is opened and the kernel is launched.

Initialization Group makes the cells in a group auto-evaluate whenever the notebook is opened and the kernel is launched.

Cell > Convert To > InputForm Display (Mathematica Menu Item)

InputForm Display displays the selection in Mathematica InputForm without interpreting it.

Cell > Convert To > InputForm (Mathematica Menu Item)

InputForm converts the selection to Mathematica InputForm.

Insert > Input from Above (Mathematica Menu Item)

Input from Above copies and pastes contents of the nearest preceding input cell.

[Right-click] > Insert New Cell (Mathematica Menu Item)

Insert New Cell creates a new cell with the selected style at the cell insertion point.

Graphics > New Graphic (Mathematica Menu Item)

New Graphic inserts an empty graphics cell at the insertion point.