First of all How to Turn ON the shortcuts !!!

Go to Profile panel in Administration > Users > Your Profile. Check the Keyboard Shortcuts checkbox to enable WordPress keyboard shortcuts for comment moderation.

List of Shortcuts!!!

j   moves the current selection (light-blue background) down
k   moves the current selection (light-blue background) up
  approves the currently selected comment
s   marks the current comment as spam
d   moves the comment to the trash (WordPress 2.9) or deletes the current comment
  restores the current comment from the trash

Shift + a    approves the checked comments
Shift + s    marks the checked comments as spam
Shift + d    deletes the checked comments
Shift + u    unapproves the checked comments
Shift + t    moves the checked comments to the Trash
Shift + z    restores the checked comments from the Trash

Publish Post:     Alt + Shift + p
Save Draft:        Ctrl + Alt + s
Preview:            Ctrl + Alt + i
Edit HTML:        Alt + Shift + e
Blockquote:      Alt + Shift + q
Insert Link:       Alt + Shift + a
Insert Image :   Alt+Shift+ M

So start using them with your WordPress