Press ~ during gameplay to display the console window. Type "DebugMode 1" (case sensitive). Then hit the ~ key again and press [Tab] to see a list of debug commands. Hitting [Tab] again will scroll through the list. Enter one of the codes below to acheive the desired result. You will see a "Success" message if you entered the cheat correctly. A "Entered Target Mode" message means you must select a character to use the cheat on. 
dm_god - God Mode 
dm_heal # - Gives you # health
dm_givegold # - Gives the # amount of gold to you
GetLevel # - Raises you an additional # of levels
GiveXP # - Get # of experience points
dm_mylittlepony - Ride a hobby horse
dm_cowsfromhell = Killer flying cows 

ModSaveFort - Set character's fortitude save modifier
ModSaveReflex - Set character's reflex save modifier
ModSaveWill - Set character's will save modifier
ModSpellResistance # - Sets your spell resistance modifier to #
SetAppearance # - Change character's race to # (you will be headless until you change back)
SetAttackBase # - Set character's base attack 

SetCON # - Sets your Constitution to #
SetWIS # - Sets your Wisdom to #
SetINT # - Sets your Intelligence to #
SetSTR # - Sets your Strength to #
SetCHA # - Sets your Charisma to #
SetDEX # - Sets your Dexternity to #
GiveXP # - Sets your Experience to #
SetAge # - Sets your Age to # 

Note: If you use a cheat on your character you must load the "nwnplayer.ini" file in the game folder and set the following lines in order to continue in your game. 

Single Player Enforce Legal Characters=0
Single Player ItemLevelRestrictions=0