For any who still play L4D2 there is a download for it that has all the Mutations unlocked for it along with custom mutations. I will post some of the mutations for it here then the rest in comment(s).

~Campaign Mutations~
Acid Trip by Rayman1103|PsyErotica
Air Raid by Rayman1103|PsyErotica
BerserkRAGE by dani1341
Big Daddy Co-Op by Tygerwoody|Rayman1103|PsyErotica
Blast Zone by Rayman1103|PsyErotica
Bleed Out by Valve
BooM60 by Rayman1103|PsyErotica
Boomer BBQ by Rayman1103|PsyErotica
Boomer Shooter by SR69MMJC
Crouch Sprinter
Chainsaw Massacre by Valve
Chainsaw Realism
Chaos by John Volkov
Classic Campaign by dani1341
Classic Mode by Thegreenthing16
Classic Special Delivery by Rayman1103
Common Problem by Rayman1103
Crowd Control
Deadliest Countdown by Rayman1103|CrazyMikeComics
Fire Storm by PsyErotica|Rayman1103
Four Swordsmen by Valve
Fully Charged by Karma Jockey
Gib Fest by Valve
Hard Eight by Valve
Hardcore Common Problems by Rayman1103
Hardcore Death's Door by Rayman1103
Hardcore Special Delivery by Rayman1103
Headshot! by Valve
Hunter Barrage by Rayman1103|PsyErotica
Hunting Party by Valve
Infestation by Rayman1103|PsyErotica
Insanity by John Volkov
Iron Man by Valve
Jockeys! by Karma Jockey
Last Gnome on Earth by Valve
Limited Resources by dani1341
Madness by DarkDragon
Panic Attack by Rayman1103
Party Hard by Rayman1103
Pitch Black Co-Op by Karma Jockey|Rayman1103
Pyromania by SuperNerd000
Realism Apocalypse by dab93
Room For One by Valve
Silent But Deadly by Karma Jockey
Snipe Fest by Karma Jockey
Spitters! by Karma Jockey
Suicide Boombers by Rayman1103
Super Hard Mode by SuperNerd000
Tank Attack by Rayman1103
Tank Bake by Rayman1103|PsyErotica
Taste of Your Own Medicine by Rayman1103|CrazyMikeComics
Ultra Realism by dani1341
Wrecking Crew by Rayman1103|PsyErotica

~Community Mutations~
Confogl by ProdigySim
Death's Door by Rayman1103
Flu Season by Karma Jockey|SR69MMJC
Nightmare by Karma Jockey
Riding My Survivor by Winded
Special Delivery by Rayman1103

~Uncommon Infected Mutations~
Biohazard
Coulrophobia
Deconstruction
Dirt Nap
Jimpocalypse
Riot Control
Uncommon Ground
Uncommon Ground Survival

~Zombie Sports League~
Monday Morning M60 Massacre!!
Monday Night Survivor Race!!
Tuesday Morning Spitter Rage!!
Tuesday Night Tank Fight!!
Wednesday Morning Riot!!
Wednesday Night Gnome Patrol!!
Thursday Morning Claw Hammer!!
Thursday Night Jockey Trouble!!
Friday Morning Explosion!!
Friday Night Friendly Fire!!
Saturday Morning Special Edition!!
Saturday Night Tankball!!
Sunday Morning Smoker Roast!!
Sunday Night Suicide Run!!

~Versus Mutations~
Big Daddy by Tygerwoody
Bleed Out Versus by Valve
Bleed Out Versus Co-Op by Rayman1103
Classic Versus by dani1341
Classic Versus Co-Op by Rayman1103
Death's Bleeding Tank by Krandel
Death's Door Versus by Rayman1103
Flame War by SuperNerd000
Green Mile
Healthpackalypse! by Valve
Hunting Party Versus by Rayman1103
Low Gravity by Rayman1103|PsyErotica
Realism Versus Co-Op by Rayman1103
Special Delivery Versus by Rayman1103
Taaannnk!! by Valve
Tankball Versus by PsyErotica|Rayman1103
Tank Busters by SuperNerd000
Twisted Tongue's by AwkwardOrpheus|Rayman1103
Versus Co-Op by Thegreenthing16|Rayman1103

The rest of the mutations are in the comment(s) to this announcement.

For any who download it be sure to check back ever so often as they update it.

All Mutations Link: http://forums.steampowered.com/forums/showthread.php?t=1529433