Press ~ during gameplay to bring up the console window, then enter the following codes:
Effect : Code
Heal players: heal # (1-100)
Kill current player: kill
Infinite ammo: happyammo
Unknown Effect: hydroshock
Give Item: giveitem X (replace X with an item from the list below)
Item List:
AQUALUNG
ARISAKA
ARISAKAOPT
BACKPACKGB1
BACKPACKGB2
BACKPACKGB3
BACKPACKGER
BACKPACKRUS
BAR
BAZOOKA
BINOCULARS
BRENGUN
CAMERA
CARBINE
CLUMMYBOMB
COLT
DEGTYAREV
DELISLE
DYNAMITE
ENFIELD
EXPLOSIVESBAG
GARAND
GRENADE36
GRENADE69
GRENADEGER
GRENADEJAP
K98
K98OPT
KNIFEGER
KNIFESAS
LEE
LEEOPT
MAGNETICMINE
MEDIKIT
MEDIKITBIG
MINE
MOSIN
MP40
MP44
PANZERFAUST
PARABELLUM
PPS
SHOTGUN
SPAGIN
SPRINGFIELD
SPRINGFIELDOPT
STENGUN
STENGUNSIL
TAISHO
TANKMINE
THOMPSON
TOKAREV
WIRECUTTER
ZB26
NOTE: Items with OPT on the end of them come with a scope. Items with SIL on the end of them are silenced.