I found this looking around, so I don't know how acurate it is. The format is screwed up but you can see the options. First number is Max number of players, then # of Xbox Systems, followed by number of players per system.
XBOX System Link and Co-op Games
System Link XBOX Games
An updated list can be find here by shadowpanther (Feb 2005) another list here.
My co-op/system-link list was last updated May 2004 and won't be updated anymore.
Game Title Max # Players # xboxes # Plyrs/ xbox
Amped 2 8 8 1
Brute Force (4co-op) 8 4 4
Crimson Skies 16 16 2
Deathrow 8 8 1
Ghost Recon 16 16 1
Ghost Recon: Island Thunder 16 16 1
Halo 16 4 4
Inside Pitch 2003 2 2 1
Mech Assault 8 8 2
Midnight Club II 8 8 1
Midtown Madness 3 8 8 1
Moto GP 16 16 4
Moto GP 2 16 16 4
Nascar Heat 2002 32 8 4
NFL Fever 2003 8 2 4
NFL Fever 2004 8 2 4
Project Gotham 2 Racing 8 8 2
Rainbox Six 3 (4co-op) 16 16 1
Return to Castle Wolfenstein 16 16 1
Sega GT Online 6 6 1
Serious Sam (4co-op) 8 (4co-op) 8 4
Soldier of Fortune 2 10 10 1
Time Splitters 2 16 4 4
Tony Hawk's Pro Skater 2X 8 8 1
Tony Hawk's Pro Skater 3 8 8 1
Tony Hawk's Pro Skater 4 8 8 1
Tony Hawk's Underground 8 8 1
Top Spin 4 2 2
Unreal Championship 6 to 10 10 4
Whacked 4 4 1
Games in bold are ones I recommend for xbox LAN parties.
Co-op XBOX Games ( system link only says yes if linkable in co-op mode)
Game Title Split Screen Shared Full Screen 4 Players System Link
Baldurs Gate: Dark Alliance . x . .
Brute Force x . x yes
Defender x . . .
Dynasty Warriors 3 x . . .
Dynasty Warriors 4 x . . .
Gauntlet: Dark Legacy . x . .
Ghost Recon x . . .
Halo x . . .
House of the Dead . x . .
Hunter: The Reckoning . x x .
LOTR: Return of the King . x . .
Medal of Honor: Rising Sun x . . .
Rainbox Six 3 . . x yes
Return to Castle Wolfenstein x . . .
Serious Sam . . x yes
Sims x . . .
Teenage Mutant Ninja Turtles . x . .
Wakeboarding Unleashed x . . .
--------------------------------------------------------------------------------
[First Person Shooters]
Halo
Halo 2
Rainbow Six 3
Rainbow Six 3: Black Arrow
Grand Theft Auto 3
GTA Vice City
[Action/Adventure]
Prince of Persia: Sands of Time
Prince of Persia: Warrior Within
[Action/Fighters]
Dead or Alive 3
Soul Calibur II
Ninja Gaiden
Def Jam Fight for NY
Guilty Gear X2 Reload (2D awesome animation)
Mortal Kombat: Deception
MechAssault 2
[Sports]
ESPN NFL2K5
NBA Ballers (1on1)
NBA Street 2 (3on3, whacky arcade)
NHL Hitz Pro (whacky arcade)
Kelly Slaters Pro Surfer
SSX 3 (snowboarding)
Top Spin (tennis)
Sega Soccer Slam (3on3, whacky arcade)
FIFA 2005 (Pro Evolution Soccer 4 is better if you can get it)
Fight Night 2004 (boxing)
Crimson Skies (airplane dogfights)
Wakeboarding Unleashed
MotoGP 2
[Car Racing]
Colin McRae Rally 2005
Burnout 3
Rallisport Challenge
Rallisport Challenge 2
[Stealth Action]
Splinter Cell
Splinter Cell: Pandora Tomorrow
Hitman 2
Hitman Contracts
[Action/Adventure]
Spiderman 2
Lord of the Rings Two Towers
LOTR Return of the King
Namco Musuem (PacMan, Ms-PacMan, Galaga, Galaxian, Dig-Dug)
Indiana Jones Emperors Tomb
[Kids]
Finding Nemo
Disney Extreme Skate Adventure (same engine as TonyHawk4)
Shark Tale
Incredibles
Sonic Mega Collection
Teenage Mutant Ninja Turtles (gameplay sucks, but 3-6yr olds will like it)
Godzilla Saves the Earth (gameplay sucks, but 3-6yr olds will like it)
Updated Feb 1, 2005