Halo 3 hidden treasures - 21 Easter Eggs in one page

What could possibly be left to discover in Halo 3?

here is a quick summary first:

EASTER EGG #1 - Actual Easter Egg
EASTER EGG #2 - "How did you do that?"
EASTER EGG #3 - Super Mario Scream
EASTER EGG #4 - Master Chief's Ancestors?
EASTER EGGS #5 and 6 - Jungle Love
EASTER EGGS #7 and 8 - Red vs. Blue
EASTER EGG #9 - Extraterrestrial Urination
EASTER EGGS #10, 11 and 12 - History Repeats
EASTER EGGS #13 and 14 - Corporate Cannibalism
EASTER EGGS #15 and 16 - Fun with Terminals
EASTER EGG #17 - Finish the Fight... Differently
EASTER EGG #18 - George Costanza Grunt
EASTER EGG #19 - The Master Bullet
EASTER EGGS #20 and 21 - Multiplayer Mop Up

And following is detailed descrioption of those recently discovered Halo 3 Easter Eggs - 21 of these, actually. Kudos go to guys from GamesRadar!
Actually, this list is already incomplete - Radarnation folks report on following thingies:
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Another service tag not allowed is N64,
another thing i noticed was that in the cutscene before the level ark, when you fly in on the pelicans when you see the ark you also see a circulair city, with a square plain behind it. I'm pretty sure its supposed to be Atlantis, as thats how it was descibed by Plato.

You are also denied from having service tags A55 and P00
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OK, so here is detailed descrioption of all Halo 3 21 Easter Eggs gather together in one page - for screenshots go check out the source.

Well... only a hidden heaping of nudity, public indecency, love letters, coded symbols, mysterious music, creepy characters, pop culture references (Mario? Seinfeld?) and other inside jokes - some hilarious, some plain bizarre - left behind by the game's sneaky creators.

Don't believe us? See for yourself on the following pages. We show you everything we and the Halo 3 community have found so far, plus how to locate them in your own game. Okay then - let's hunt some Egg!

We'll start with three of the toughest eggs. These are so difficult to recreate, in fact, that we've left it to the fan community to demonstrate them for you.

EASTER EGG #1 - Actual Easter Egg

A shimmering sphere of mysterious numbers hidden high, high, high above the multiplayer desert of Sandtrap. A coded map to secret treasure, or simply some forgotten programming? For a closer look, you'll need to use a tricky combination of Forge, Theater, teleporters and sentinels to push yourself through the map's locked barrier.

EASTER EGG #2 - "How did you do that?"

Halo 3's creators know how to reward the hard work - and the inspired madness - of their fans. So if you manage to overturn the largest vehicle in the game with a little luck and a whole lot of explosives, you'll receive some humorously impressed feedback.

EASTER EGG #3 - Super Mario Scream

Nintendo's mascot in Microsoft's mascot's adventure? The mind reels. But watch - no, listen - to these three pieces of evidence. Sounds to us like the distinctive death of the world's most distinctive plumber. "Yawwwwhoooohoooohooooo!"

We've gotten the nearly impossible stuff out of the way. With our helpful videos and screens, you should have no trouble discovering the rest of these 21 Easter Eggs for yourself. Starting at the beginning of the game...

EASTER EGG #4 - Master Chief's Ancestors?

The last thing we expected to stumble across in a science fiction epic full of aliens, cyborgs, spaceships and AI constructs was a hairy, knuckle-dragging family of prehistoric cavemen holding teddy bears. Yet here they are... and here's how to locate them in the first mission, Sierra 117. Shoot those creepy, frozen-faced Neanderthals in the face for us, won't you?

EASTER EGGS #5 and 6 - Jungle Love

We've already waxed poetic about the underlying love story in Halo 3. But the gooey mushiness isn't exclusive to Master Chief and Cortana. Sprinkled throughout the dense foliage of the first mission, Sierra 117, are carved hearts with initials and dates. Clearly, the overworked developers were feeling a tad guilty about their lonely wives and girlfriends at home.
Big Screen, Main Screen

EASTER EGGS #7 and 8 - Red vs. Blue

If you're a fan of the Halo-inspired machinima series Red vs. Blue, you'll definitely want to track these two Eggs down. The first is stupid easy - just stare closely at the tire of any Warthog in the game. Does that say "Puma"? As in, what Grif suggests calling the jeep because it looks more like that animal?

Even better is the secret conversation that takes place down a deserted hallway in the Crow's Nest mission. After you go through a door and see a Warthog explode in front of you, fight through the Grunts and continue forward, skipping the open doorway on the left. At the end of the passage, you'll witness two Marines arguing over a password. Depending on the difficulty you selected, the characters will be either Tucker and Doc, Simmons and Grif, or Church and Caboose... all of Red vs. Blue fame

EASTER EGG #9 - Extraterrestrial Urination

We knew Brutes were, well, brutish... but we had no idea they were this disgusting. You've definitely run into this guy on The Ark mission before, but you probably smacked him upside the head before you actually realized what he was doing. Take a look - it's pretty unmistakable. Now wipe the smug and shameless satisfaction right off his face.

EASTER EGGS #10, 11 and 12 - History Repeats

Halo wasn't the first game Bungie made, you know. Before Master Chief was a glint in some artist or programmer's eye, the company was releasing classic fare like Myth and Marathon. They haven't forgotten their roots. In one of our favorite Halo 3 Easter Eggs, you can hear the piano theme from Myth - "Siege of Madrigal" - by standing in a distant corner of The Covenant mission. This lovely piece of music was hidden in the first two Halo games as well.

Then there are the Marathon symbols. Guilty Spark and the sentinels of Forge have got 'em - right in their eyes. You can also make out the icon on many of Halo 3's weapons. We think we see it on the Spartan Laser below... do you?

EASTER EGGS #13 and 14 - Corporate Cannibalism

Bungie may enjoy trumping their past successes, but they also love poking fun at themselves... or at least their boss. Jason Jones, the company's co-founder, is positively roasted throughout Halo 3. "Missing Person" notices with his name and likeness are scattered in various levels, like The Storm and Floodgate. The one below was found in the first big open area of The Storm, near the far door.

Much more embarrassing, however, is the likeness of Jason Jones tucked away in a shadowy corner of the final mission. Damn, that dude must be cold. To reach him and then laugh at him, you'll need a PhD in grenade or rocket jumping. Our preferred method, requiring two players, is spelled out in the video below.


EASTER EGGS #15 and 16 - Fun with Terminals

If you made your way through our Terminals Video Guide, you already saw one of these. The optional eighth terminal on the Cortana mission reveals extra dialogue, including a veiled reference to the Ghosts of Onyx book. If that's not an Easter Egg, we don't know what is.

You also would have visited the seventh terminal on the final mission (hidden, actually, in the same place as Floating Underwear Man). But were you on Legendary difficulty at the time? If you weren't, you missed some of the most important story material in the game. The screen below is NOT it... that's what you see on any other difficulty level. You know you want to be "worthy"...

EASTER EGG #17 - Finish the Fight... Differently

Did you race across the final mission of Halo 3 thinking, "Yeah, this is cool and all. But wouldn't it be way cooler on a Mongoose?"

You're right - it would be. So here's how to get one before the crucial chase. The Arbiter has never looked so awesome and ridiculous at the same time. Be warned, this makes the ride much wilder and much more unpredictable. We love it.

EASTER EGG #18 - George Costanza Grunt

This charming fellow awaits you near the very end of the last mission. When Cortana says "90% left, Chief," that's your cue to start searching for him. Our video will guide you straight and true.

"The jerk store called and they're all out of you!" This could be the most adorable Easter Egg in gaming history. George Costanza Grunt, can we adopt you?

EASTER EGG #19 - The Master Bullet

Man, you thought the Master Chief was badass before? Wait until you catch a microscopic glimpse at his bullet casings. The dude friggin' etches his name into each and every one. No, seriously. Where does he get this kind of time? Doesn't he have some giant glowing rings to blow up? Whatever, we're still in awe.

EASTER EGGS #20 and 21 - Multiplayer Mop Up

Here's one you can try from the menu screen. Choose "I17" ("i" as in the letter) for your multiplayer service tag. Oops! Seems that that particular code is already taken... by UNSC SPARTAN 117. You might know him as Master Chief... Oh well, better go for some immature "69" tags instead.

Finally, check out your Halo 3 Service Record on Bungie.net. Amidst all the Killing Sprees and Killtaculars (you get those, right?), you might notice a funny little cow named "Steaktacular!"

According to Halopedia, the medal is "earned by winning a multiplayer game by 20 or more kills. The description, 'Luke owes you a steak dinner', comes from a Bungie Humpday Challenge where a steak dinner was bet over a game, in which Will bet that he could beat another team, led by Mike, by at least 20 points. He lost 50-5." Ouch.