At my hospital:
Code Blue: Cardiac/Pulmonary arrest
Code Purple: Pedi arrest (doesn't usually get called overhead)
Code Pink: Infant Abduction
Code Red: Fire-Can't miss this one due to loud alarms/flashing lights and doors closing.
Code Yellow: Think this one is hazardous substance spill/contamination stuff.
Code Black: Bomb threat (or probably any other threat)
Code Green: Physical assistance needed asap...(usually for psych patients, upset and unruly family members, or a variety or ER patients-psych, ETOH, substance abuse, etc)
All of our codes are printed on the back of our name badges.
Most common: Blue, Green, Red, and Pink "for practice"