there's a easter egg in vice city... literally and easter EGG. if you jump through a specific wall, you'll end up in a room with a big brown egg in it, and it says "'happy easter" on the egg

The Zoo level in Turok: evolution. Go in the cheats menu and enter "Zoo"

The two flowers in Kirby Air Ride's City Trial mode.

in Batman: Arkham Asylum, there's a secret room that you have to blast open in a certain place. It contains plans that teases it's next game, Arkham City. 

I would have to say either the talking Grunt that tells you John's history in Halo 3 or the monkey family in Halo 3.
    Or the skulls. I think they're a sort of easter egg all on their own (halo 3 of course)

The one I like the most is Halo 3's Red vs. Blue Easter Egg. Pretty much anyone who's played the game's campaign mode knows about this one. On the level "Crow's Nest", after clearing out the enemies in the first area that has them, instead of turning down into a hallway, the player can continue to the end of the tunnel, where the player will find a lone soldier pounding on the door requesting more ammo, while the person on the other side refuses. The characters are voiced by the same people who make the RvB web series. What they say and which characters' voices/personalities they have vary depending on the difficulty level.

In Mario Kart 8 I think I may have found one, I'll have to play the track again to verify it but...

In the track "Sunshine Airport" there's an area high off the ground on a hovering piece of track. As your kart leaps off this track and heads back down to the airport, look off to the right in the far distance at a series of islands - I could swear one is shaped like the Koopa Troopa beach as seen in Mario Kart 64, if not that then it's definitely a Koopa-shaped rock formation anyway

It has to be the elevator rave in Crysis 2.

I always liked the Mario Paintings in Ocarina of Time in the castle courtyard and in Lego City Undercover you can find a working bullet bill and a very well hidden Wiggler among other things.

There's a statue in Super Mario 64 located inside the castle.  It's in the room with the ghosts.  Written on the statue are letters that are difficult to make out.  There's much controversy as to what the letters say.  I find it interesting!  Have you ever heard about this?

In Grand Theft Auto: San Andreas, there's a giant bridge.  Once you have a jet pack, you can fly to the top of it.  Written at the top, it says: "There are no Easter Eggs up here.  Go away."

In Metal Gear Solid, you fight a boss named Psycho Mantis.  He claims he can read your mind.  (Actually, he can read your memory card!)  If you have a saved game file of Symphony of the Night on your memory card, Psycho Mantis will say, "You like Castlevania, don't you?"