Everyone's favorite videogame easter eggs?

I was playing Arkham Asylum and tried out the easter egg for that game (the preview to Arkham City). I was wondering if anyone had a favorite easter egg from any game they have ever played. Descriptions and pictures are welcome. I have to think about this question so I may not post mine until later.

In Perfect Dark Zero and in Punisher for PS2 there are great Half-Life references. In both instances it is the player overhearing conversations between 2 scientists. Now that I think about it, that may not have been The Punisher game. But the scientists were in Tony Starks facility. So it was something Marvel.
 
[EDIT] I found a video. It was the Punisher game.

Probably being in the Insomniac museum in a few Ratchet & Clank games.

I think the punisher game may even use headcrabs. I'm going to go find video.
 
[EDIT]
http://www.youtube.com/watch?v=5oLSoLJN_yE    At the 40 second mark
 
I can't find a video of the PDZ one.

I like the Star Wars easter egg in Morrowind.

Everyone knows the "duck behind the block" part for Mario 3, but I think that one is pretty awesome.

I like the Bungie Tribute Room in Reach.  Pretty Awesome

This one's pretty cool: 

I think the punisher game may even use headcrabs. I'm going to go find video.
 
[EDIT]
http://www.youtube.com/watch?v=5oLSoLJN_yE    At the 40 second mark   I can't find a video of the PDZ one.

Here is an old one people might not know, in Rebel Assault II (yes I know that game was not that good, bear with me) you could enter in a secret code that would change the game into a MST3K type thing. Three heads would be silhouetted at the bottom of the screen, and the voices would be muted, and subtitles would pop up with silly dialogue. It was kinda dumb, but cool at the time.

I kinda liked being rewarded with boobs in the Leisure Suit Larry games. Those were the best easter eggs for a 12 year old.

I kinda liked being rewarded with boobs in the Leisure Suit Larry games. Those were the best easter eggs for a 12 year old.

Has to be John Romero's head in Doom 2, he's part of the final boss and must be shot to win. Can't get any better than that.
 

  This right here. Flipped my shit when I first came upon it.

The troll with the suicide note under the bridge in Oblivion was pretty hilarious the first time I stumbled upon it. 
 
  

The troll with the suicide note under the bridge in Oblivion was pretty hilarious the first time I stumbled upon it. 
 
  

I dunno if this counts, but in MGS when you keep calling Mei Ling on the codec and hanging up. And then she becomes silent and then sticks her tongue out. That always stuck with me as a very endearing and human moment.

Yesterday i found the giant giant purple bunny in Saints Row 2, and definitely wasn't expecting it.

Finding and wearing the GTAIII protagonist's clothing in GTAIV was pretty awesome.

Has to be John Romero's head in Doom 2, he's part of the final boss and must be shot to win. Can't get any better than that.
 

 
 
 
 
 
 
 
 
 
 

The most recent Easter egg that I really liked would be the bubble blaster in Just Cause 2, completely useless in actual fire fights but shooting bubbles when your riding at incredible speeds on top of a jet...pretty cool. Also, there are a ridiculous amount of Easter eggs in that game.

Best easter egg ever in a video game is being able to microwave the hamster in Maniac Mansion.

Of recent memory, the secret singing turrets in Portal 2. Also, the missing ship.

"That's one Doom'd space marine!" 
 
Yeah, it's an oldie, but still a goodie.

Anything involving the Konami code was normally a laugh.

Best easter egg ever in a video game is being able to microwave the hamster in Maniac Mansion.

I liked finding The Hatch (from Lost) in Xmen Origins: Wolverine.

Magicka is like one giant, long easter egg, so that.