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
a 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
z 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