Cell > Cell Properties > Active (Mathematica Menu Item)

Active toggles a cell between active and inactive states.

Insert > Table/Matrix > Add Column (Mathematica Menu Item)

Add Column adds a column at the cursor's insertion point in a table or matrix.

Insert > Table/Matrix > Add Row (Mathematica Menu Item)

Add Row adds a row at the cursor's insertion point in a table or matrix.

Cell > Cell Properties > Evaluatable (Mathematica Menu Item)

Evaluatable toggles a cell between evaluatable and unevaluatable. Only evaluatable cells can be sent to the kernel.

Insert > Table/Matrix > Make Spanning (Mathematica Menu Item)

Make Spanning combines the selected entries from a formatted grid into a single spanning entry.

Insert > Object... (Mathematica Menu Item)

Object opens a dialog to insert an embedded object, such as a bitmap image, spreadsheet, or document file, at the insertion point (Windows only).

Cell > Cell Properties > Open (Mathematica Menu Item)

Open toggles a cell between open and closed.

Insert > Picture (Mathematica Menu Item)

Picture inserts a picture from a file or inserts an empty graphic at the insertion point.

Insert > Table/Matrix > Split Spanning (Mathematica Menu Item)

Split Spanning divides a spanning entry from a formatted grid into separate entries.

Format > Text Color (Mathematica Menu Item)

Text Color assigns a color to selected cells or text.