Bring DOWN the console and enter "sv_cheats 1"

Effect - Code

All weapons and ammo - impulse 101
Enemies don't attack - notarget
Infinite power for your suit - infinite_aux_power
Kill all npc's in the area - npc_kill
No damage - god
Never Die - buddha
Skulls - impulse 102
Spawn a scout car - ch_createjeep
Spawn an airboat - ch_createairboat
Walk through walls - noclip