Okay, I'll put up your votes in the morning. Night.

I'll Do more when I can think

N64
1-Ocarina of Time 
2-Mario 64
3-Perfect Dark
4-Mario Kart 64
5-Conker's Bad Fur Day

PSX
1-Final Fantasy VIII
2-Metal Gear Solid
3-Parasite Eve
4-Chrono Cross
5-Xenogears

PS2
1-Final Fantasy X
2-Metal Gear Solid 2
3-Final Fantasy X-2
4-Shadow Hearts 2
5-Persona 3

PSP
1-Metal Gear Solid: Peace Walker
2-The Legend of Heroes: Trails in the Sky
3-The 3rd Birthday
4-Tactics Ogre
5-Final Fantasy VII: Crisis Core

DS
1-Dragon Quest V
2-The World Ends With You
3-Pokemon Black/White
4-New Super Mario Bros
5-Pokemon Platinum

PS3
1-Wipeout HD Fury
2-Demon Soul's
3-Final Fantasy XIII
4-Valkyria Chronicles
5-Metal Gear Solid 4

Xbox 360
1-Lara Croft and the Guardian of Light
2-Mass Effect 2
3-Gears of War
4-Gears of War 2
5-Fable 2

NES: SMB, SMB3, Zelda, Metroid, Dragon Quest

GB: Pokemon R/B/G, Tetris, SM Land, Zelda LA, Pokemon G/S

MD/Gen: Sonic, Sonic 3, Sonic 2, Strider, Shining Force

SNES: FFVI, Zelda ALttP, Chrono Trigger, Super Metroid, Terranigma

SEGA CD: Sonic CD, Wing Commander, Snatcher, Lunar, Power Rangers

Saturn: Guardian Heroes, Grandia, Radiant Silvergun, Panzer Dragoon, NiGHTS

PSX: Metal Gear Solid, FFVII, GT, Crash Bandicoot, Resident Evil

N64: Super Mario 64, Zelda OoT, Goldeneye, Super Smash Bros, Mario Kart 64

GBC: Pokemon Crystal, Zelda OoA/S, Kirby TnT, Pokemon Pinball, Shantae

DC: Sonic Adventure, Skies of Arcadia, Grandia II, Sonic Adventure II, Soul Calibur

GBA: Pokemon R/S, Advance Wars, Metroid Fusion, Golden Sun, FFVI Advance

PS2: MGS2, GTA3, FFX, S of the C, Okami

GC: SSBM, Metroid Prime, Zelda WW, Tales of Symphonia, RE4

XB: Halo, Halo 2, Fable, Shenmue 2, GTA: SA

DS: NSMB, Nintendogs, Brain Training, TWEWY, Pokemon B/W

PSP: FFVII CC, Jean D'arc, GT, MGS:PW, VC2

360: Gears, Halo 3, CoD4, Bioshock, LO

Wii: Wii Sports, NSMBWii, MKWii, SSBB, MH3

PS3: MGS4, LBP, Uncharted, GoW3, VC

Hum.... How can 2 Sonic Adventures games have defined the Dreamcast?  There's a difference between what you think defined a console, and what games were your favorites...  

NES:

1- Super Mario Bros

2- Super Mario Bros 3

3- Megaman

4- Contra

5- Megaman 3

Genesis:

1- Sonic & Knucles

2- Looney Toones: Acme All Stars

3- Streets of Rage

4- Comix Zone

5- Shinning Force

SNES:

1- The Legend of Zelda: A link to the past

2- Super Mario RPG

3- Donkey Kong Country 2

4- Super Mario World 2: Yoshi's Story

5- Super Mario Kart

PSX:

1- Metal Gear Solid

2- Final Fantasy VII

3- Final Fantasy Tactics

4 - Resident Evil 2

5- Gran Turismo

N64:

1- Super Mario 64

2- The Legend of Zelda: Ocarina of Time

3- Golden Eye

4- Wave Race 64

5- Star Fox 64

Wii:

1- Super Mario Galaxy 2

2- Donkey Kong Country Returns

3- Fire Emblem: Radiant Dawn

4- NSMB Wii

5- Punch Out Wii

PS3:

1- Uncharted

2- Red Dead Redemption

3- Demon's Souls

4- Bioshock

5- Heavy Rain

Note to PS3: I didn't include Dragon Age Origins nor Mass Effect games cause I played them on PC, but those would have been on my PS3 top 5 expelling Bioshock and Heavy Rain.

Nintendo Entertainment System (NES)

• Super Mario Bros.
• Contra
• Super Mario Bros. 3
• The Legend of Zelda
• Dragon Quest

Nintendo Gameboy (GB)

• Tetris
• Pokemon Blue/Red/Yellow
• The Legend of Zelda: Link's Awakening
• Tetris Attack
• Final Fantasy Adventure

Sega Genesis (Gen)

• Sonic the Hedgehog 3
• Ristar
• Streets of Rage II
• Ecco the Dolphin
• Michael Jackson's MoonWalker

Super Nintendo Entertainment System (SNES)

• Final Fantasy VI
• Street Fighter II
• Super Mario World
• Super Metroid
• Chrono Trigger

Sony Playstation 1 (PS/PSX)

• Final Fantasy VII
• Tekken 3
• Crash Bandicoot 3
• Final Fantasy VIII
• Metal Gear Solid

Nintendo 64 (N64)

• Super Mario 64
• Goldeneye 007
• Mario Kart 64
• Perfect Dark
• Super Smash Bros.

Nintendo Gameboy Color (GBC)

• Pokemon Gold/Silver
• Pokemon Trading Card Game
• Pokemon Pinball
• Mario Tennis
• Wario Land 3

Sega Dreamcast (DC)

• SoulCalibur
• Shenmue
• Crazy Taxi
• Jet Grind Radio
• Marvel vs. Capcom 2

Nintendo Gameboy Advance (GBA)

• Golden Sun
• Metroid Fusion
• Pokemon Ruby/Sapphire
• Castlevania: Aria of Sorrow
• Final Fantasy V Advance
  

Sony Playstation 2 (PS2)

• Final Fantasy X
• Grand Theft Auto III
• Devil May Cry
• Shadow of the Colossus
• Grand Theft Auto III: San Andreas

Microsoft X-Box (XB)

• Halo: Combat Evolved
• Ninja Gaiden
• Shenmue II
• Halo 2
• Dead or Alive 3

Nintendo Gamecube (GCN)

• Resident Evil 4
• Super Smash Bros. Melee
• Metroid Prime
• The Legend of Zelda: Wind Waker
• SoulCalibur II

Nintendo Duel Screen/Developer System (NDS)

• WarioWare: Touched!
• Nintendogs
• Final Fantasy IV
• Rhythm Heaven
• New Super Mario Bros.

Sony Playstation Portable (PSP)

• Lumines
• Crisis Core: Final Fantasy VII
• Wipeout Pure
• Patapon
• Tekken: Dark Resurrection

Microsoft X-Box 360 (360)

• Halo 3
• The Elder Scrolls IV: Oblivion
• Gears of War
• Call of Duty 4: Modern Warfare
• Mass Effect 2

Sony Playstation 3 (PS3)

• LittleBigPlanet
• Heavy Rain
• Wipeout HD
• Uncharted 2: Among Thieves
• Demon's Souls

Nintendo Wii (Wii)

• Wii Sports
• Super Mario Galaxy
• Wii Fit
• Super Smash Bros. Brawl
• Super Mario Galaxy 2

This is not a list of my favorite or the best games in the system. It's a list of games that I associate with the system no matter how good or bad they are, or whether it's exclusive or multiplatform.

Awww. Good thing some of you put the abreviations for the systems next to their full names, we gamers would have been lost without those. lol :P

Seems like some people think this thread is a "your top 5 games per system" thread, which, by my understanding, it isn't.

NES:

1) Super Mario Bros.

2) Super Mario Bros. 3

3) The Legend of Zelda

4) Duck Hunt

5) Mega Man 2 (Hate to put this on the list instead of my beloved MM3, but 2 definitely caused more of an impact.)

Game Boy:

1) Tetris

2) Pokémon Red/Blue

3) Super Mario Land

4) Kirby's Dream Land

5) The Legend of Zelda: Link's Awakening

Genesis:

1) Sonic the Hedgehog

2) Mortal Kombat

3) Sonic the Hedgehog 2

4) Street Fighter II: The World Warrior

5) Streets of Rage

SNES:

1) Super Mario World

2) Donkey Kong Country

3) Street Fighter II: The World Warrior

4) The Legend of Zelda: A Link to the Past

5) Super Metroid

PS:

1) Final Fantasy VII

2) Gran Turismo

3) Metal Gear Solid

4) Tekken 3

5) Crash Bandicoot

N64: (Obvious list is obvious)

1) Super Mario 64

2) The Legend of Zelda: Ocarina of Time

3) GoldenEye 007

4) Mario Kart 64

5) Super Smash Bros.

Dreamcast:

1) Sonic Adventure

2) Marvel vs. Capcom 2: New Age of Heroes

3) SoulCalibur

4) Phantasy Star Online

5) Shenmue

GBA:

1) Pokémon Ruby/Sapphire

2) Pokémon FireRed/LeafGreen

3) Advance Wars

4) Super Mario Advance

5) Sonic Advance

PS2:

1) Grand Theft Auto III

2) Grand Theft Auto: San Andreas

3) Gran Turismo 4

4) Grand Theft Auto: Vice City

5) Ratchet & Clank

Xbox:

1) Halo: Combat Evolved

2) Halo 2

3) Tom Clancy's Splinter Cell

4) Fable

5) Star Wars: Knight of the Old Republic

GC:

1) Super Smash Bros. Melee

2) Resident Evil 4

3) Metroid Prime

4) Prince of Persia: The Sands of Time

5) Animal Crossing

DS:

1) New Super Mario Bros.

2) Brain Age: Train Your Brain in Minutes a Day

3) Nintendogs

4) Mario Kart DS

5) Pokémon Diamond/Pearl

X360:

1) Halo 3

2) Call of Duty: Modern Warfare 2

3) Call of Duty 4: Modern Warfare

4) Grand Theft Auto IV

5) Call of Duty: Black Ops

PS3:

1) Call of Duty: Modern Warfare 2

2) Call of Duty 4: Modern Warfare

3) Grand Theft Auto IV

4) Gran Turismo 5

5) Call of Duty: Black Ops

Wii:

1) Wii Sports

2) New Super Mario Bros. Wii

3) Wii Fit

4) Super Smash Bros. Brawl

5) Wii Play

psx:

1.) ff7

2.) metal gear solid

3.) gran turismo

4.) crash bandicoot 3

5.) tomb raider

Hmm...

Nes

1 - Super Mario Bros 3
2 - Excitebike
3 - Megaman 5
4 - Ninja Gaiden 2
5 - TMNT 2

Sega Genesis

1 - Sonic 2
2 - Phantasy Star 4
3 - Shining Force
4 - Street of Rage 2
5 - Road Rash

Super Nintendo

1 - Super Mario World
2 - Street Fighter 2
3 - Final Fantasy VI
4 - Chrono Trigger
5 - Star Fox

Sega CD

1 - Sewer Shark
2 - Lunar
3 - Snatcher
4 - Dark Wizard
5 - Lunar 2

Saturn

1 - Panzer Dragoon 2 Zwei
2 - Shining the Holy Ark
3 - Daytona USA
4 - Virtua Fighter 2
5 - Street Fighter Alpha 2

Playstation

1 - Final Fantasy VII
2 - Gran Turismo
3 - Resident Evil
4 - Tekken 2
5 - Tomb Raider 2

Dreamcast

1 - Soul Calibur
2 - Shenmue
3 - Sonic Adventure
4 - Skies of Arcadia
5 - Jet Grind Radio

Playstation 2

1 - Gran Turismo 3
2 - Metal Gear Solid 2
3 - Devil May Cry 3
4 - Final Fantasy XII
5 - Star Ocean 2

Gamecube

1 - Resident Evil 4
2 - F-Zero GX
3 - Super Smash Bros
4 - Soul Calibur 2
5 - Star Wars Rogue Squadron

Xbox

1 - Halo CE
2 - Ninja Gaiden Black
3 - Project Gotham 2
4 - Splinter Cell Chaos Theory
5 - Conker's Bad Fur Day Reloaded

Xbox 360

1 - Halo Reach
2 - Gears of War 2
3 - Mass Effect
4 - TES IV: Oblivion
5 - Forza Motorsports 3