Sound files of that incomparable voice...
Wavs:

"If you only knew the power of the Dark Side..."

"I have you now!"

"I sense something.  A presence I have not felt since..."

"Give yourself to the Dark Side."

"Don't be too proud of this technological terror you've constructed."

"The Emperor is not as forgiving as I am."

"Your destiny lies with me."

*gak* *choke*  "You have failed me for the last time, Admiral."

[Boba Fett has doubts...]  "The Empire will compensate you if he dies.  Put him in!"

"Don't make me destroy you."

"You may dispense with the pleasantries, Commander.  I am here to put you back on schedule."
 
New ones from Bith Sith!

"Don't fail me again."

"Impressive!"

"We would be honored if you would join us."

"Now I am the master."

"What is thy bidding, my master?"

"I am your father."

"The Force is with you, young Skywalker.  But you are not a Jedi yet."

Lightsaber igniting...

TIE Fighter...

Breathing...
 
From Kelraa:  "I find your lack of faith disturbing."

From DarthMari:  "If you will not fight, then you will meet your destiny!"

MIDI:
 

The Imperial March
 

MP3:
 
The Imperial March
 
From Lady Maul:

Another Imperial March

The Imperial March - Metallica

The Imperial March - No Doubt

Vader's Funeral

"If you only knew the power of the Dark Side!"

"What is thy bidding, my master?"
 
 
Vader arrives on the second Death Star "Lord Vader!  This is an unexpected pleasure.  We are honored by your presence." 
"You may dispense with the pleasantries, Commander.  I'm here to put you back on schedule." 
"I assure you, Lord Vader, my men are working as fast as they can." 
"Perhaps I can find new ways to motivate them." 
"I tell you, this station will be operational as planned." 
"The Emperor does not share your optimistic appraisal of the situation." 
"But he asks the impossible.  I need more men." 
"Perhaps you can tell him when he arrives." 
"The Emperor's coming here?" 
"That is correct, Commander, and he is most displeased with your apparent lack of progress." 
"We shall double our efforts!" 
"I hope so, Commander, for your sake.  The Emperor is not as forgiving as I am." 
 
 
The Emperor's Arrival "Rise, my friend." 
"The Death Star will be completed on schedule." 
"You have done well, Lord Vader.  And now I sense you wish to continue your search for young Skywalker." 
"Yes, my master." 
"Patience, my friend.  In time he will seek you out.  And when he does, you must bring him before me.  He has gown strong.  Only together can we turn him to the Dark Side of the Force." 
"As you wish." 
"Everything is proceeding as I have foreseen." 
 
 
 
Master and Friend  "What is thy bidding, my master?" 
"Send the fleet to the far side of Endor.  There it will stay until called for." 
"What of the reports of the Rebel fleet massing near Sullust?" 
"It is of no concern.  Soon the rebellion will be crushed and young Skywalker will be one of us.  Your work here is finished, my friend.  Go out to the command ship and await my orders." 
"Yes, my master." 
 
 
I Have Foreseen It "I told you to remain on the command ship." 
"A small Rebel force has penetrated the shield and landed on Endor." 
"Yes, I know." 
"My son is with them." 
"Are you sure?" 
"I have felt him, my master." 
"Strange that I have not.  I wonder if your feelings on this matter are clear, Lord Vader." 
"They are clear, my master." 
"Then you must go to sanctuary moon and wait for him." 
"He will come to me?" 
"I have foreseen it.  His compassion for you will be his undoing.  He will come to you, and then you will bring him before me." 
"As you wish."