Left 4 Dead cheats

1st go to your options and enable your console
2nd open up your console by pressing the ~ button below the esc
type sv_cheats 1 on your console and you're free to do ANYTHING! xD

spawning mobs:
spawn hunter : z_spawn hunter
spawn boomer :z_spawn boomer
spawn smoker :z_spawn smoker
spawn witch:z_spawn witch
spawn tank : z_spawn tank
spawn horde ; z_spawn horde

usefull cheats :
give health : give health
molotov ; give molotov
pipebomb ; give pipe_bomb
first aid kit ; give first_aid
pills ; give pain_pills
ammo ; give ammo
warping survivors ; warp_all_survivors_here
start a fire ; fire
spawn a pipebomb below you ; boom
spawn both pipe bomb and molotov below you ; boom fire
shotgun ; give shotgun
rifle ; give rifle
sniper ; give hunting rifle
automatic shotgun ; give autoshotgun
pistol ; give pistol

GODLIKE CHEATS!
godmode ; god 1
infinite ammo ; sv_infinite ammo 1
go through walls and fly around! ; noclip

well these are all the cheats i know and discovered but anyways feel free to tell me more then i can post it here..