Group Cells/Group Together makes a group out of the selected sequence of cells.

Grouping opens a submenu to control cell grouping and toggle cells open or closed.

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.

InputForm converts the selection to Mathematica InputForm.

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

New opens a dialog for generating a table or matrix.

Notebook History displays a time record of changes made in the input notebook.

Page Break inserts a page break at the horizontal I-beam.

Parallel Kernel Status opens a dialog with statistics on active parallel kernels.