View Menu

Show Canvas Only
Only shows the canvas and what you have configured to show in Canvas Only Settings
Fullscreen mode
This will hide the system bar.
Wrap Around Mode
This will show the image as if tiled orthographically. Very useful for tiling 3d textures. Hit W to quickly activate it.
Instant Preview
Toggle Instant Preview globally.
Soft Proofing
Activate Soft Proofing.
Out of Gamut Warnings
See the Soft Proofing page for details.
Canvas

Contains view manipulation actions.

Mirror View This will mirror the view. Hit M to quickly activate it. Very useful during painting.

Show Rulers
This will display a set of rulers. mouseright the rulers after showing them, to change the units.
Rulers track pointer
This adds a little marker to the ruler to show where the mouse is in relation to them.
Show Guides
Show or hide the guides.
Lock Guides
Prevent the guides from being able to be moved by the cursor.
Show Status Bar
This will show the status bar. The status bar contains a lot of important information, a zoom widget, and the button to switch Selection Display Mode.
Show Grid
Shows and hides the grid. Ctrl + Shift + '
Show Pixel Grid
Show the pixel grid as configured in the Display Settings.
Snapping
Toggle the Snapping types.
Show Painting Assistants
Shows or hides the Assistants
Show Painting Previews
Shows or hides the Assistants