Lets you move and drag
selections and layers through the one or more documents. It is also used
to align shapes and layers.
Notes Tool
Cs,Cs2,Cs3
Shift + N
Allows you to add
notes by clicking somewhere in your document, then add the text on it.
Audio Annotation
Cs,Cs2,Cs3
Shift + N
Allows you add audio
notes to your documents by just clicking anywhere and record your voice.
Ruler Tool
Cs,Cs2,Cs3
Shift + I
The measure tool allows
you to calculate a distance between 2 points, where you click on the
fist point then drag to the next. The calculation appears in the
info palette
Count Tool
New in CS3
Shift + I
This tool is used to
count objects in an image, by just clicking on the objects while
Photoshop adds a cumulative number to each one.
Hand Tool
Cs,Cs2,Cs3
Shift + H
This told helps to drag
through an image that is not completely visible in your document (for
it's larger than the space you set), just click and move your mouse and
the image would move with your mouse direction.
Zoom Tool
Cs,Cs2,Cs3
Shift + Z
This tool is used to zoom
in and out of your image. You can use
Ctrl + Plus key(+) to zoom-in or Ctrl+ Minus key (-)
to zoom out. You can also shift between zooming in to zooming out by
pressing the ALT key.
Lets you move and drag
selections and layers through the one or more documents. It is also used
to align shapes and layers. 
Allows you to add
notes by clicking somewhere in your document, then add the text on it. 
Allows you add audio
notes to your documents by just clicking anywhere and record your voice. 
The measure tool allows
you to calculate a distance between 2 points, where you click on the
fist point then drag to the next. The calculation appears in the
info palette
This tool is used to
count objects in an image, by just clicking on the objects while
Photoshop adds a cumulative number to each one. 
This told helps to drag
through an image that is not completely visible in your document (for
it's larger than the space you set), just click and move your mouse and
the image would move with your mouse direction.
This tool is used to zoom
in and out of your image. You can use
Ctrl + Plus key(+) to zoom-in or Ctrl+ Minus key (-)
to zoom out. You can also shift between zooming in to zooming out by
pressing the ALT key.